Research Article| Volume 19, ISSUE 1, P66-71, January 2013

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# Self reported adherence to a home-based exercise programme among people with Parkinson's disease

Published:August 08, 2012

## Abstract

### Background

There is an extensive literature addressing compliance with medication, techniques to measure, and ways to improve it. In comparison the literature concerning adherence to exercise programmes agreed with a physiotherapist is limited.

### Objective

We estimate the percentage of exercise repetitions completed of those agreed with a physiotherapist in the context of a six week personalized exercise programme to reduce falling in people with Parkinson's disease, and examine patient characteristics that predict adherence.

### Methods

Secondary analysis of data collected during a randomized controlled trial. Participants allocated to receive the exercise programme self-reported the number of repetitions of prescribed strengthening, range of movement and balance exercises they had completed in daily dairies. Indoor or outdoor walking was also prescribed but in terms of target distances or lengths of time, and was not included in our analysis.

### Results

On average the 70 participants allocated to the exercise programme reported completing 79% (95% confidence interval 73%–86%) of the prescribed number of repetitions of their exercises. The percentage of exercises completed varied depending on the specific exercise prescribed, and on participant characteristics: those who were older, in poorer health and with anxiety, depression, or mental heath problems reported lower adherence to exercise.

### Conclusion

Several of the factors we found to reduce adherence to exercise have been shown by others to reduce compliance with antiparkinsonian medication, but we found adherence decreased with age in contrast to the pattern of better compliance with medication amongst older people with Parkinson's disease reported previously.

## 1. Introduction

In comparison to the literature addressing [
• Grosset K.A.
• Bone I.
• Grosset D.G.
Suboptimal medication adherence in Parkinson's disease.
] and refining measures [
• Elm J.J.
• Kamp C.
• Tilley B.C.
• Guimaraes P.
• Frase D.
• Deppen P.
• et al.
Self-reported adherence versus pill count in Parkinson's disease: the NET-PD experience.
] of compliance with antiparkinsonian medication there is little or no research quantifying engagement, or lack of it, with exercises prescribed to people with Parkinson's Disease (PD), or more widely in the older population. Allen et al. [
• Allen N.E.
• Sherrington C.
• Suriyarachchi G.D.
• Paul S.S.
• Song J.
• Canning C.G.
Exercise and motor training in people with Parkinson's disease: a systematic review of participant characteristics, intervention delivery, retention rates, adherence, and adverse event in clinical trials.
] in their review of trials of exercise and motor training in people with PD found that adherence was infrequently reported and in some cases was artificially elevated by including only participants who completed the intervention. In this paper we use the term ‘adherence’ in line with health psychology [
• Horne R.
• Weinman J.
Predicting treatment adherence: an overview of theoretical models.
] to describe engagement with, and practice of rehabilitation strategies agreed with a physiotherapist, whereas the term ‘compliance’ is used in relation to medication. Bassett [
• Bassett S.F.
The assessment of patient adherence to physiotherapy rehabilitation.
] reviewed estimates from a number of studies concluding that up to 65% of patients may be non-adherent or only partially adherent to home rehabilitation programmes. Various methods have been considered to measure adherence to home-based exercise [
• Bassett S.F.
The assessment of patient adherence to physiotherapy rehabilitation.
,
• Vitolins M.Z.
• Rand C.S.
• Rapp S.R.
• Ribisl P.M.
• Sevick M.A.
Measuring adherence to behavioral and medical interventions.
], including self report assessments in a variety of formats and measurements based on devices or equipment such as calorimetry, pedometers or accelerometers: the practicality of the various approaches depending on patient context. Self-report was recommended [
• Bassett S.F.
The assessment of patient adherence to physiotherapy rehabilitation.
] as the ideal method of measuring adherence to home-based exercises, and the use of daily diaries may reduce any inaccuracy due to recall. Diary information should yield estimates of adherence to exercise in terms of the percentage of prescribed repetitions completed, however only a few studies have described adherence in this way. Schneiders et al.[
• Schneiders A.G.
• Zusman M.
• Singer K.P.
Exercise therapy compliance in acute low back pain.
]used this approach in their study of exercise compliance in people with acute low back pain and found that people who received illustrated reinforcement of prescribed exercises had a significantly higher adherence rate (77%) than those who received verbal instruction alone (38%): while Bassett and Petrie[
• Bassett S.F.
• Petrie K.J.
The effect of treatment goals on patient compliance with physiotherapy exercise programmes.
]found adherence to exercise performed by people with limb injury to be 72% in a group randomized to have treatment goals set collaboratively between physiotherapist and patient, 56% in the group with goals set solely by the physiotherapist, and 77% in the group with no formally set goals, with results differing depending on type of deficit. A recent systematic review of quantitative research addressing barriers to adherence with various aspects of physiotherapy at outpatient clinics including attendance at appointments, adherence with home exercises or in-clinic adherence, highlighted a number of predictors of poor adherence including low levels of physical activity, psychological factors and socio-demographic factors [
• Jack K.
• McLean S.M.
• Klaber-Moffett
• Gardener E.
Barriers to treatment adherence in physiotherapy outpatient clinics: a systematic review.
]. There is substantial qualitative literature examining attitudes to exercise in older populations with many factors proposed as influencing engagement with exercise [
• Booth M.L.
• Owen N.
• Bauman A.
• Clavisi O.
• Leslie E.
Social-cognitive and perceived environmental influences associated with physical activity in older Australians.
,
• Allender S.
• Cowburn G.
• Foster C.
Understanding participation in sport and physical activity among children and adults: a review of qualitative studies.
,
• Horne M.
• Speed S.
• Skelton D.A.
• Todd C.
What do community dwelling Caucasian and South Asian 60–70 year olds think about exercise for fall prevention?.
]. Three studies specific to people with PD emphasise the importance of perceived control over disease symptoms and progression [
• Ravenek M.J.
• Schneider M.A.
Social support for physical activity and perceptions of control in early Parkinson's disease.
,
• Quinn L.
• Busse M.
• Khalil H.
• Richardson S.
• Rosser A.
• Morris H.
Client and therapist views on exercise programmes for early-mid stage Parkinson's disease and Huntingdon's disease.
,
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
], social support [
• Ravenek M.J.
• Schneider M.A.
Social support for physical activity and perceptions of control in early Parkinson's disease.
,
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
] and the need for personalized programmes [
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
], whilst therapists expressed concern for the safety of their clients performing exercises [
• Quinn L.
• Busse M.
• Khalil H.
• Richardson S.
• Rosser A.
• Morris H.
Client and therapist views on exercise programmes for early-mid stage Parkinson's disease and Huntingdon's disease.
].
Early work [
• Sluijs E.M.
• Kok G.J.
• van der Zee J.
Correlates of exercise compliance in physical therapy.
] emphasised the importance of disease specific characteristics such as prognosis and degree of hindrance as influences on adherence. In the current study we examine adherence specific to people with PD, presenting the number of repetitions reported as completed in daily diaries as a percentage of those prescribed in the intervention arm of a randomized controlled trial of an individually tailored exercise programme [
• Ashburn A.
• Fazakarley L.
• Ballinger C.
• Pickering R.M.
• McLellan D.L.
• Fitton C.
A randomised controlled trial of a home-based exercise programme to reduce risk of falling among people with Parkinson's disease.
] which found consistent trends to lower rates of falling and repeat falling immediately following the intervention and four months later. We examine whether the percentage of repetitions reported varies across the type of exercise prescribed and with patient characteristics such as age, gender and severity of disease. We conclude by contrasting factors influencing adherence to exercise with those reported [
• Grosset K.A.
• Bone I.
• Grosset D.G.
Suboptimal medication adherence in Parkinson's disease.
] to be predictors of compliance with antiparkinsonian medication.

## 2. Methods

### 2.1 The exercise programme

A menu of specific exercises and functionally based activities to reduce the risk of falling was devised by physio- and occupational therapists based on experience, the literature including two Cochrane reviews [
• Deane K.H.O.
• Jones D.
• Clarke C.
• Playford E.D.
• Ben-Shlomo Y.
Physiotherapy for patients with Parkinson's disease.
,
• Deane K.H.O.
• Jones D.
• Ellis-Hill C.E.
• Playford E.D.
• Ben-Shlomo Y.
Comparison of physiotherapy techniques for patients with Parkinson's disease.
], and a series of focus groups with clinicians. The menu (Table 1) comprised exercises in four groups: 1) muscle strengthening, 2) range of movement, 3) balance training, and 4) walking (labels for specific exercises are given in the first column of Table 1). Each exercise was graded at six progressive levels enabling increasing challenges, and tailoring of exercises to the individual following assessment. Leaflets with written instructions and images were prepared to facilitate correct performance of the exercises/activities. The programme also included strategies and advice concerning fall prevention; movement initiation and compensation; fall avoidance in relation to footwear, eyesight and turning; coping with a fall; medication and falls; and the appropriate use of walking aids.
Table 1Menu of progressive exercises for strengthening and range of movement
Number of repetitions and size of any weights to be individually tailored by the physiotherapist to meet the patient's need.
.
ExerciseLevel 1Level 2Level 3Level 4Level 5Level 6
Group 1 strengthening
1A – QuadsStatic quadsSitting: 90° knee flexion to full extensionAs level 2 with weightIncrease repetitions with weightIncrease weightIncrease repetitions with weight
1B – Quads functionalSit to stand from average height chairIncrease repetitions (no use of hands)Sit to stand from a lower chair/stoolIncrease repetitions (change foot position)Step upsStep ups: increase repetitions
1C – Hip extensorsCrook lying: Knee rollingCrook lying: bridgingStanding at sink: hip extensionIncrease repetitionsStanding at sink: extension with weightsIncrease repetitions
1D – Hip abductorsSupine lying: abduction on sliding boardSide lying: abduction against gravityStanding: abduction without weightStanding: abduction with weightIncrease repetitionsIncrease weight
1E – Hip abductors functionalStanding: weight transfer with knee straightStanding: weight transfer with knee bentSide stepping: holding furniture for supportSide stepping: no support & increase repetitionsLateral step upsLateral step ups: Increase repetitions
Group 2 Range of movement
2A – Ankle movementsIn lying: dorsi- & plantar flexionIn sitting: dorsi- & plantar flexionIn sitting: slide heel backwardsIn standing: LungingHeel dips: off the edge of a stepIncrease repetitions
2B – Pelvic tiltSitting: anterior/posterior tiltingIncrease repetitionsCrook lying: anterior/posterior tiltingIncrease repetitionsStanding: anterior/posterior tiltingIncrease repetitions
3C – Pelvic tilt functionalSitting: lateral weight transferenceSitting: bottom walkingStanding: weight transferenceStanding: sideways steppingWalkingTurning
2D – Trunk movementsSitting: upper trunk rotationCrook lying: knee rollingRolling in lyingStanding: trunk rotationTurningIncrease repetitions (figure of eight)
2E Head movementsSitting: cervical spine side flexionSitting: cervical spine rotationStanding: cervical spine side flexionStanding: cervical spine rotationWalking: with head rotationWalking: with head rotation
Group 3 Balance
3A – ReachingSitting: forward reachingSitting: sideways reachingStanding: forwards reachingStanding: sideways reachingIncrease repetitionsIncrease distance reached
3B – StaticSit to standSit to stand from lower chairIncrease repetitionsIncrease speedStand to half sitProgress to a lower chair
3C – DynamicSide steppingHeel to toe walkingCross steppingBackwards steppingCombine levels 1–4 & change directionProgress to more fluent changes
3D – FunctionalWalking in a figure of eightWalking & picking object up from the floor & replacingStepping up & down a stepTurning 180°/360°Walking & talkingWalking & carrying
Group 4 Walking
4A – Indoors & turningWalking along hallway: close to the wall (set repetitions)Walking along hallway: away from wall (set repetitions)Walking along hallway: close to the wall (faster speed)Walking along hallway: away from wall (faster speed)Walking along hallway with larger steps (count steps)Walking along hallway with larger steps (count steps on the turn)
4B – Outdoors10 min normal speed20 min normal speed30 min normal speed30 min × 2 a week30 min × 3 a week30 min × 3 a week
a Number of repetitions and size of any weights to be individually tailored by the physiotherapist to meet the patient's need.

### 2.2 The trial

The trial has been described elsewhere [
• Ashburn A.
• Fazakarley L.
• Ballinger C.
• Pickering R.M.
• McLellan D.L.
• Fitton C.
A randomised controlled trial of a home-based exercise programme to reduce risk of falling among people with Parkinson's disease.
,
• Ashburn A.
• Pickering R.M.
• Fazakarley L.
• Ballinger C.
• Fitton C.
• McLellan D.L.
Recruitment to a clinical trial from the databases of specialists in Parkinson's disease.
]: it was approved by the East Dorset Local Research Ethics Committee (LREC number: 13/00/S; ISRCTN 63503875). To be eligible, independently mobile people living at home in the community had to have had a confirmed diagnosis of idiopathic PD, experienced more than one fall in the previous 12 months, and passed a screening test for gross cognitive impairment. Potential participants were excluded if they were unable to participate in assessment due to pain or if they had an acute medical condition and were in receipt of, or soon to receive, treatment. After giving informed consent, participants were randomized to receive the exercise programme delivered by a single research physiotherapist or usual care. The analysis reported here is restricted to the 70 participants allocated to the exercise programme which took place during 2002–2004: 38 (54%) were male; their mean age was 73 years (min–max 44–91 years); they had been diagnosed with PD for on average 7.7 years (min–max 1–31 years); the majority 62 (89%) were taking L dopa plus; while 36 (49%) were taking dopamine agonists. Summary statistics with respect to characteristics considered as predictors of adherence in this study are shown in the second column of Table 4. Participants were not asked to stop other exercise classes: in the intervention arm 17 (24%) were receiving PD related rehabilitation at baseline and the percentage remained similar at the 8 weeks and 6 months assessments [
• Ashburn A.
• Fazakarley L.
• Ballinger C.
• Pickering R.M.
• McLellan D.L.
• Fitton C.
A randomised controlled trial of a home-based exercise programme to reduce risk of falling among people with Parkinson's disease.
]. Between randomisation and 6 months 46 (73%) of the 63 participants in the intervention group for whom information was available had fallen compared to 78% in the control group (P = 0.645); 7/67 (10%) had sustained an injury requiring medical help compared to 16% in the control group (P = 0.329); and 2/67 (3%) had sustained a fracture compared to 9% in the control group (P = 0.141) [
• Ashburn A.
• Fazakarley L.
• Ballinger C.
• Pickering R.M.
• McLellan D.L.
• Fitton C.
A randomised controlled trial of a home-based exercise programme to reduce risk of falling among people with Parkinson's disease.
].
Participants in the exercise group were visited at home by the trial physiotherapist for a target of six weekly 1 h sessions: although additional visits were possible at the discretion of the therapist they were not anticipated to be necessary in the majority of cases. Spouses or relatives living with the participants (carers) were encouraged to be present during all visits and to support the participant in their exercise programme, in line with more recent findings concerning the importance of social support [
• Ravenek M.J.
• Schneider M.A.
Social support for physical activity and perceptions of control in early Parkinson's disease.
]. Following assessment at the start of each session, treatment goals were agreed with the participant and carer if present. Exercises were selected from the menu, taught by the trial physiotherapist with the aid of the leaflets, and participants were encouraged to exercise an agreed number of repetitions each day until the next session. The intention was to prescribe a variety of exercises (up to 4 per week), usually achieved by selecting an exercise from each of the four groups in Table 1, but occasionally the therapist might prescribe more than one exercise from the same group depending on presentation. In particular there was an emphasis on walking, either indoors or outdoors if possible. The therapist aimed to progress each exercise prescribed across successive visits depending on the assessment and a participant's feedback on the ease of completing the exercises prescribed the previous week (week 2 onwards), either by prescribing an exercise at a higher level, or by increasing the number of repetitions at the same level, or a combination of both, but always within safe limits. If a participant achieved maximal levels of an exercise or the therapist deemed them to be making no progress, a participant might be moved to a different exercise within the same or a different group possibly changing the number of exercises prescribed to above or below four.

### 2.3 Data collection

At the start of the trial, baseline characteristics of the participants were recorded using established measurements for use in studies of PD including: disease severity using the Hoehn and Yahr stage [
• Hoehn M.
• Yahr M.
Parkinsonism; onset, progression and mortality.
]; the motor examination from the Unified Parkinson's Disease Rating Scale (UPDRS) [
• Lang A.
• Fahn S.
Assessment of Parkinson's disease.
] (0–108; low = good); the Berg Balance Test [
• Berg K.
• Wood-Dauphinee S.
• Williams J.
• Gayton D.
Measuring balance in the elderly; preliminary development of an instrument.
] (0–56; high = good); functional reach [
• Duncan P.
• Weiner D.
• Chandler J.
• Studenski S.
Functional reach: a new clinical measure of balance.
] being the difference between arm's length and maximal forward reach with fixed base of support in cms (high = good); the impact of disability using the self-assessment PD scale [
• Wade D.T.
Measurement in neurological rehabilitation.
] based on ratings of ability to carry out 25 everyday tasks between ‘able to do alone without difficulty’ and ‘unable to do at all’ yielding a total score taking values between 25 and 125 (low = good); any mental health problems mentioned by the patient at baseline; and the self completed thermometer (a visual analogue scale) of state of health on the day of questioning rated between 0 (worst imaginable health state) and 100 (best imaginable health state), along with the pain/discomfort and anxiety/depression questions (each rated none, moderate or extreme) from the EuroQuol EQ-5D [
• EuroQuol Group
EuroQuol – a new facility for the measurement of health related quality of life.
]. The mobility, self-care and usual activities questions of the EQ-5D were not examined.
A diary was given to each participant, and the therapist encouraged both participant and their carer in timely completion of the number of repetitions of each prescribed exercise completed. At the next visit the therapist reviewed and discussed the diary record always emphasising the importance of accuracy of reporting. Participants/carers completed the diaries for the duration of the home-based sessions. The reported number of repetitions of muscle strengthening, range of movement and balance exercises are the focus of the analysis of adherence in terms of the ratio of reported to prescribed repetitions carried out here: walking prescriptions were often in terms of length of time, or a target distance in a participant's locality, and were not amenable to this approach. We call the target number of repetitions agreed between physiotherapist and client the ‘prescribed’ number, to make a clear distinction from the number reported by participants in their diaries as completed - the ‘reported’ number. At the end of the trial a clinical judgement of progression or not in each exercise prescribed was made by the therapist reviewing the changing level or number of repetitions prescribed, the participant's report of carrying out the exercises in their diary, or any other relevant information. Progression in each exercise prescribed for 4 weeks or more was also rated as occurring if the level prescribed in the final week was higher than that in the first week or, if the level did not change, the prescribed number of repetitions increased.

### 2.4 Statistical analysis

Summary statistics were used to describe the participants and exercises prescribed. Numbers of daily exercise repetitions prescribed, and reported by a participant, were totaled over the 6 days (excluding the day on which the home visit took place) of each of the six weeks of the programme, to give weekly prescribed (Prep) and reported (Rrep) numbers of repetitions, and we measured adherence as the ratio of reported to prescribed repetitions $(Rrep/Prep)$. Where a participant reported zero repetitions over a week the value of Rrep was replaced by 1. Geometric means of the $(Rrep/Prep)$ ratio across the participants prescribed each exercise in each week were calculated. In order to present the impact of patient characteristics as multiplicative effects yielding percentage increases or decreases the following statistical model was considered for the natural logarithm (ln) of the $(Rrep/Prep)$ ratio at the level of weekly values per participant per exercise:
$ln(RrepPrep)=exercise+β1∗week+β2∗x,$

where exercise is a factor indicating the 14 non-walking exercises, β1 is a regression parameter allowing for linear increase or decline over the 6 weeks of the programme, and β2 is a vector of regression parameters allowing for an influence from baseline covariates (x). We also investigated the possibility of β1 varying across levels of another factor such as exercise. Exponentiating the formula gives
$ratio=RrepPrep=eexercise∗eβ1week∗eβ2∗x.$

Exponentiated parameter estimates are interpreted as multiplicative effects on the $(Rrep/Prep)$ ratio specific to each exercise, or as a relative ratio (RR) between categories of a categorical factor. 95% confidence intervals (CI) for RRs were obtained by exponentiating the limits of model-based CIs. The model was fitted in PROC MIXED in SAS 9.1 using restricted maximum likelihood (REML). The approach to modeling follows that recommended by Brown & Prescott [
• Brown H.
• Prescott R.
Applied mixed models in medicine.
]: we started by comparing different variance structures for two fixed effects models, the first including only the exercise term, the second additionally included the exercise*week interaction. The likelihood of models incorporating variance structures successively including random participant effects, random participant*week slopes, and random participant*exercise*week slopes were examined. For both fixed effects models the variance structure with random intercept and slope across weeks for each participant had highest likelihood and lowest Akaike information criterion and was used in all subsequent modeling. Fixed terms were tested for inclusion using the Kenward-Roger adjustment [
• Brown H.
• Prescott R.
Applied mixed models in medicine.
].
The sensitivity of results to the replacement of zero Rrep values by 1, was evaluated by: omitting zeros from the analysis, replacing them with 0.5, and replacing them with 5. Results (not reported) were similar when zeros were replaced by 0.5 and 5, but there were differences when zeros were omitted from the analysis which removes individuals with worst adherence from consideration.

## 3. Results

### 3.1 Exercises prescribed

Of the 70 participants allocated to the intervention arm of the trial, 66 received six treatment sessions, 1 received 2 sessions, 1 received 3 sessions, and only 2 subjects received a seventh session. At the first session the majority, 52 (74%) of participants were prescribed a unique combination of exercises, and no single combination was prescribed to more than three participants. In Table 2 the level and total number of repetitions prescribed at week 1 are shown for each exercise. Some exercises were started at level 1 for all the participants, but particularly hip extensor and abductor exercises tended to be commenced at higher levels. Typically between 60 and 120 repetitions were prescribed in total for the week (that is between 10 and 20 per day). Walking was set for all but 3 of the participants, and for 48 (69%) outdoors walking was prescribed. In the final row of the table it can be seen that the majority of participants (83%) were prescribed 4 exercises during the first week. Of the total 207 exercises prescribed to the 70 participants, the therapist retrospectively rated 179 (86%) to have demonstrated progression in her clinical judgement: while the participant progressed to a higher level or more repetitions in 189 (85%) of the 202 exercises prescribed for 4 weeks or more.
Table 2Exercises prescribed in week 1, their level, and number of repetitions for the week (n = 70).
ExerciseNumber (%) set exerciseLevel setNumber repetitions mean min–max
123456
Group 1 Strengthening
1A Quads3 (4%)3120

120–120
1B Quads functional12 (17%)1277

60–150
1C Hip extensors34 (49%)71755101

60–240
1D Hip abductors21 (30%)8265126

60–240
1E Hip abductors functional6 (9%)42120

60–240
GROUP 2 Range of movement
2A Ankle movements12 (17%)91295

60–120
2B pelvic tilt13 (19%)1376

30–120
2C Pelvic tilt functional3 (4%)3120

120–120
2D Trunk movements21 (30%)16574

30–120
2E Head movements10 (14%)9199

60–120
Group 3 Balance
3A Reaching out of base of support16 923%)12486

60–120
3B Static23 (33%)2360

18–90
3C Dynamic19 (27%)17258

30–120
3D Functional17 (24%)1660

30–240
Group 4 Walking
4A Indoors and turning20
One participant was prescribed both indoor and outdoor walking.
(29%)
NA
Walking prescribed in various formats to suit the participant.
NA
Walking prescribed in various formats to suit the participant.
4B Outdoors48
One participant was prescribed both indoor and outdoor walking.
(69%)
NA
Walking prescribed in various formats to suit the participant.
NA
Walking prescribed in various formats to suit the participant.
Number of exercises/participant: 7 (10%) three exercises; 58 (83%) four exercises; 5 (7%) five exercises.
a One participant was prescribed both indoor and outdoor walking.
b Walking prescribed in various formats to suit the participant.

### 3.2 Adherence

One participant did not complete their diary and was omitted from the analysis of adherence, a further nine reported zero repetitions for an exercise for at least one week with a total of 20 (1.6%) zeros out of the total of 1239 weekly, exercise-specific diary reports. In Table 3 the geometric means of $(Rrep/Prep)$ ratios for each week and exercise, demonstrate no clear trend of increase or decline over weeks (P = 0.3376), nor of trend over weeks differing across exercises (P = 0.8030).
Table 3Geometric mean$(Rrep/Prep)$ ratios in weeks 1–6 and estimated from the statistical model (number available and with zero
n is the number prescribed the exercise, and nzero is the number reporting zero repetitions replaced by 1.
).
Week 1Week 2Week 3Week 4Week 5Week 6Estimated $(Rrep/Prep)$ ratio (CI)
Group 1 Strengthening
1A0.17 (n = 3, nzero = 1)0.63 (n = 3)0.68 (n = 3)0.38 (n = 2)0.67 (n = 1)0.83 (n = 1)0.49 (0.35, 0.68)
1B0.92 (n = 12)0.67 (n = 12)0.88 (n = 12)0.93 (n = 12)0.84 (n = 13)0.79 (n = 13)0.79 (0.68, 0.93)
1C0.77 (n = 33)0.77 (n = 33)0.71 (n = 32)0.62 (n = 32, nzero = 2)0.77 (n = 32)0.57 (n = 32, nzero = 2)0.78 (0.80, 0.87)
1D0.60 (n = 20, nzero = 1)0.59 (n = 19)0.82 (n = 19)0.82 (n = 18)0.83 (n = 18)0.67 (n = 17, nzero = 1)0.71 (0.62, 0.81)
1E1.07 (n = 6)1.09 (n = 6)1.27 (n = 6)0.90 (n = 6)0.77 (n = 6)0.89 (n = 6)0.99 (0.81, 1.23)
Group 2 Range of movement
2A0.96 (n = 12)0.88 (n = 12)0.94 (n = 11)0.89 (n = 10)0.90 (n = 9)0.90 (n = 9)0.97 (0.82, 1.14)
2B0.91 (n = 13)0.57 (n = 14, nzero = 1)0.87 (n = 14)0.75 (n = 14)0.64 (n = 14, nzero = 1)0.55 (n = 13, nzero = 2)0.71 (0.61, 0.82)
2C0.87 (n = 3)0.94 (n = 3)0.79 (n = 3)1.00 (n = 3)1.05 (n = 3)1.00 (n = 3)0.81 (0.60, 1.09)
2D0.98 (n = 21)0.81 (n = 21)0.91 (n = 20)0.64 (n = 19, nzero = 1)0.69 (n = 19)0.64 (n = 18, nzero = 1)0.77 (0.68, 0.88)
2E0.87 (n = 10)0.88 (n = 10)1.00 (n = 10)0.90 (n = 10)0.77 (n = 10)0.90 (n = 10)0.90 (0.76, 1.06)
Group 3 Balance
3A0.72 (n = 16)0.73 (n = 16)0.77 (n = 16)0.57 (n = 16, zero = 1)0.71 (n = 16)0.53 (n = 15, zero = 1)0.75 (0.65, 0.86)
3B0.67 (n = 22)0.75 (n = 22)0.71 (n = 22)0.70 (n = 22, nzero = 1)0.85 (n = 22)0.63 (n = 22, nzero = 2)0.81 (0.71, 0.91)
3C0.86 (n = 19)0.86 (n = 19)0.85 (n = 19)0.85 (n = 20)0.91 (n = 20)0.87 (n = 19, nzero = 1)0.84 (0.73, 0.95)
3D1.00 (n = 17)0.97 (n = 17)0.77 (n = 16)0.83 (n = 16)0.82 (n = 16)0.94 (n = 16)0.80 (0.70, 0.93)
a n is the number prescribed the exercise, and nzero is the number reporting zero repetitions replaced by 1.
The overall $(Rrep/Prep)$ ratio was estimated to be 79% (73%, 86%), indicating that participants typically performed about 20% fewer repetitions than prescribed. Examining the 1239 diary reports revealed 24 (1.9%) instances where a participant performed twice or more of the repetitions prescribed: 11 of them related to one individual (a 70 year old man with Hoehn & Yahr score of II) who over-performed all non-walking exercises from week 2 onwards. The $(Rrep/Prep)$ ratio differed depending on the exercise in question (P < 0.0001). In Table 3 the lowest ratio was for quads exercises (IA), but this estimate was based on only three participants. The ratio was also low for hip abductors (1D), pelvic tilt (2B), hip extensors (1C), trunk movements (2D), reaching out of base of support (3A) and quads functional (1B).
In Table 4 we explore the impact of personal characteristics on the $(Rrep/Prep)$ ratio. The ratio decreased with increasing age, being 10% lower per 10 year increase in age. Though differences between men and women were not statistically significant, there was a trend of men performing 15% more repetitions than women (P = 0.0771). The differences between the categories of living status (alone, partner, family/friends, other) were small and not statistically significant. The $(Rrep/Prep)$ ratio was generally lower in people with poorer physical state. Statistically significant RRs were found with increasing UPDRS motor examination, self assessed disability, Berg balance test, functional reach, EQ-5D state of health thermometer and for the EQ-5D pain/discomfort question, all being in the direction of lowering the percentage of repetitions performed with poorer health. Finally a pattern emerged of people with anxiety or depression or a mental health problem performing a reduced number of their prescribed exercises.
Table 4The impact of personal characteristics on the $(Rrep/Prep)$ ratio.
CovariateMean (SD) min–max or number (%) (n = 70)RR
RR: relative (Rrep/Prep) ratio.
(CI)
P
Kenward-Roger adjusted P value.
Age multiplicative decrease per 10 years73 (10)

44–91
0.90 (0.83, 98)0.0137
GenderMale38 (54%)1.15 (0.98, 1.36)0.0771
Female32 (46%)1.00
Living statusAlone18 (26%)1.000.6959
Partner43 (61%)1.05 (0.87, 1.28)
Family/friends8 (11%)0.90 (0.68, 1.21)
Other11.02 (0.51, 2.04)
Year since PD diagnosis multiplicative decrease per 10 years7.7 (5.8)

1–31
0.95 (0.83, 1.09)0.4701
Hoehn & Yahr stageII8 (11%)1.18 (0.91, 1.52)0.2908
III44 (63%)1.00
IV18 (26%)0.94 (0.77, 1.13)
UPDRS motor exam multiplicative decrease per 10 points19 (8)

3–33
0.90 (0.81, 1.01)0.0766
Self assessment disability scale multiplicative decrease per 10 points56 (13)

36–98
0.91 (0.86, 0.96)0.0020
Berg balance test multiplicative increase per 10 points44 (10)

13–56
1.14 (1.05, 1.24)0.0018
Functional reach multiplicative increase per 10 cm23 (7)

6–38
1.14 (1.01, 1.28)0.0324
Mental health problem13/69 (19%)0.80 (0.66, 0.99)0.0363
EQ-5DNo pain or discomfort16 (23%)1.000.0181
Moderate pain or discomfort48 (69%)0.90 (0.75, 1.09)
Extreme pain or discomfort6 (9%)0.64 (0.47, 0.87)
EQ-5DNot anxious or depressed33 (47%)1.000.0002
Moderately anxious or depressed34 (49%)0.84 (0.72, 0.97)
Extremely anxious of depressed3 (4%)0.47 (0.33, 0.68)
EQ-5D state of health thermometer multiplicative increase per 10 points63 (17)

16–95
1.05 (1.01, 1.11)0.0190
a RR: relative $(Rrep/Prep)$ ratio.
b Kenward-Roger adjusted P value.

## 4. Discussion

We found high self reported rates of adherence (79%) to an individually tailored programme of exercise, but there was variation in the extent of adherence depending on the exercise in question. Aspects of the exercise that may impact on adherence include the difficulty in carrying it out [
• Quinn L.
• Busse M.
• Khalil H.
• Richardson S.
• Rosser A.
• Morris H.
Client and therapist views on exercise programmes for early-mid stage Parkinson's disease and Huntingdon's disease.
], its perceived relevance [
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
], and whether it is perceived to be tedious, amongst others. These issues provide a counterpart to the factors thought to affect compliance with medication and the tolerability of individual drugs. Deciding suitable exercises for a patient, taking into account their likely adherence, is a central issue for physiotherapists, and the approach to deciding on an exercise strategy has been shown to impact on rates of adherence [
• Bassett S.F.
• Petrie K.J.
The effect of treatment goals on patient compliance with physiotherapy exercise programmes.
]. A positive patient–therapist relationship is crucial, influencing the quality and appropriate quantity of information and feedback given, providing emotional support, and increasing motivation [
• Bassett S.F.
The assessment of patient adherence to physiotherapy rehabilitation.
,
• Ravenek M.J.
• Schneider M.A.
Social support for physical activity and perceptions of control in early Parkinson's disease.
,
• Quinn L.
• Busse M.
• Khalil H.
• Richardson S.
• Rosser A.
• Morris H.
Client and therapist views on exercise programmes for early-mid stage Parkinson's disease and Huntingdon's disease.
,
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
,
• Sluijs E.M.
• Kok G.J.
• van der Zee J.
Correlates of exercise compliance in physical therapy.
]. The interplay between physical, psychological and situational factors is likely to be complex and approaches adopted, and their success, may differ depending on the therapist concerned. Our study was limited to only one therapist and so we were unable to examine the possibility that the percentage of repetitions performed by their patients differs across therapists, although such variation could easily be accommodated in the statistical model. Though adherence may vary across therapists, the patterns in adherence associated with patient characteristics reported could apply within therapists. In the recent systematic review of the quantitative literature concerning barriers to treatment adherence in physiotherapy outpatient clinics, Jack et al. [
• Jack K.
• McLean S.M.
• Klaber-Moffett
• Gardener E.
Barriers to treatment adherence in physiotherapy outpatient clinics: a systematic review.
] conclude that the existing literature focuses on patient characteristics and that further research into health professional and health organisational factors would be appropriate.
We demonstrated that adherence to exercise is influenced by patient characteristics. In contrast to Grosset et al. [
• Grosset K.A.
• Bone I.
• Grosset D.G.
Suboptimal medication adherence in Parkinson's disease.
] who showed compliance to antiparkinsonian medication to be poorer at younger age, we found the percentage of repetitions performed to be worse for older participants. Participants with poorer physical condition in terms of the UPDRS motor examination, the Berg balance test, functional reach, self assessed severity of disease, the EQ-5D state of health thermometer and those in pain also completed fewer of their prescribed number of repetitions. Grosset et al. report poorer compliance with medication associated with poorer quality of life (as measured by the PDQ39 [
• Peto V.
• Jenkinson C.
• Fitzpatrick R.
PDQ-39: a review of the development, validation and application of a Parkinson's disease quality of life questionnaire and its associated measures.
]), but not with UPDRS, cognitive state or daytime sleepiness. Like Grosset et al. who reported poorer compliance with worse depression as measured by the geriatric depression score [
• Yesavage J.A.
• Brink T.L.
• Rose T.L.
• Lum O.
• Huang V.
• Adey M.B.
• et al.
Development and validation of a geriatric depression screening scale: a preliminary report.
], we also found those reporting anxiety and depression on the EQ-5D and those with a mental health problem noted at the start of the trial performed a reduced number of their prescribed repetitions.
The analysis reported here is based on a self completed daily diary recording the number of repetitions of exercises completed, and it is possible our findings in part reflect patterns of reporting. Concerns have been raised over the accuracy of reported health experiences in paper diaries, particularly in relation to achieving narrow time windows [
• Stone A.A.
• Shiffman S.
• Schwartz J.E.
• Broderick J.E.
• Hufford M.R.
Patient non-compliance with paper diaries.
]. There was no necessity in our trial for participants to either exercise at a particular time of day, or to complete the diary immediately after exercising. Bassett [
• Bassett S.F.
The assessment of patient adherence to physiotherapy rehabilitation.
] mentions an advantage of diaries is that they may provide an aide memoire encouraging patients to perform their exercises, but also warns that the advantage can be viewed as a limitation to the generalizability of results beyond the research context where diary completion is not carried out.
We studied adherence to exercise over a relatively short period of time (6 weeks), and found no overall trend of increase or decline in the percentage of repetitions performed over the 6 weeks, but there was evidence of variation across patients in this respect which remained unexplained in our model. Perseverance with exercising in the long term is likely to be much poorer than adherence in the short-term [
• Sluijs E.M.
• Knibble J.J.
Patient compliance with exercises: different theoretical approaches to short-term and long-term compliance.
]. It would be useful to map the ratio of repetitions performed to prescribed over a longer period in people with PD. Ene et al. [
• Ene H.
• McRae C.
• Schenkman M.
Attitudes toward exercise following participation in an exercise intervention study.
] also report that adherence dropped after completion of their exercise programme and highlight the importance of ongoing support for people with PD to continue exercising in the face of the barriers in everyday life. However the quality of diary reporting might also diminish after the intensive phase of an exercise programme, confounding patterns of adherence with trends in self reporting.
In conclusion, participants typically completed a high percentage 79% (73%, 86%) of the repetitions agreed with their physiotherapist. Whether this good performance reflects the patient group, the short-term and supervised nature of the exercises we studied, or the method of measuring adherence is not clear. The percentage of exercises completed varied across the specific exercises and depended on participant characteristics: those who were older, in poorer health and with anxiety/depression/mental heath problems reported lower adherence to exercise.

None.

## Acknowledgements

Data used in this study was collected in a trial funded by Action Medical Research and the John and Lucille Van Geest Foundation. Thanks are due to the participants of the trial who made this study possible.

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