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Refill compliance rates: evidence for use as an outcome measure in practice-based research

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The Pharmaceutical Journal Vol 265 No 7114 September 16, 2000
Pharmacy Practice Research
Papers presented at the British Pharmaceutical Conference,Birmingham, September 10 to 13, 2000 pR35

Refill compliance rates: evidence for use as an outcome measure in practice-based research

By I. K. Sturgess, C. M. Hughes and J. C. McElnay

Introduction Research has documented that a number of factors affect a patient's medicine-taking behaviour.1 There is still much controversy within the literature regarding the measurement of non-compliance, however. The refill records of computerised patient medication records (PMRs) have been increasingly used as an objective, indirect and valid source of compliance information within pharmacy practice research.2 However, few studies have used records to measure outcomes of pharmacist interventions. Therefore, the aims of the research were to confirm the validity and to investigate the use of refill records of PMRs as a method of measuring change in compliance, thereby enabling the outcome of pharmacist interventions to be assessed.

Methods Data used in this analysis were collected as part of a larger community pharmacy based intervention study where a structured pharmaceutical care programme, encompassing compliance-improving interventions, was provided to intervention patients while control patients received "normal services".3 Patients were recruited at baseline (110 intervention, 79 control) and 86 intervention and 61 control patients were followed up at six months. PMRs were used to calculate refill compliance rates, for each long-term prescribed medicine using the following formula:


A refill compliance rate of between 80 and 120 per cent4 was deemed as adequate compliance: lower rates indicated under-compliance and rates over 120 per cent represented over-compliance. Refill compliance rates were calculated for six months prior to recruitment and during the first six months of the study. To determine aspects of construct validity, hypothesis testing was used to determine which patient and medicine-related factors influenced the measure. Changes in compliance over time were assessed by analysing differences in compliance between control and intervention patients using appropriate statistical tests.

Focal points

  • The aim of the research was to investigate the use of refill records from computerised patient medication records (PMRs) as a method of measuring change in compliance, thereby enabling the outcome of pharmaceutical interventions to be assessed
  • PMRs were used to calculate refill compliance rates for each long-term prescribed medicine
  • Medicine-related factors such as complexity of drug regimen were found to influence compliance
  • Using the refill compliance rates, compliance improved in intervention patients following pharmaceutical care provision
  • Refill compliance rates, as calculated from PMRs may be used to measure improvement in compliance as an outcome of pharmacist intervention

Results In total, 1,171 medicines were reported at baseline. Rates of refill compliance could be calculated for 64.4 per cent of medicines and rates ranged from 17.5 to 396.0 per cent. The refill compliance rate did not fall within the specified limits (80-120 per cent) for 37.4 per cent of medicines (21.1 per cent under-compliant and 16.3 per cent over-compliant). There were differences between different classes of medicines, for example non-compliance was higher for musculoskeletal and respiratory medicines compared with cardiovascular medication. At baseline, patients were compliant with 62.4 ± 34.0 per cent of their medicines, but only 30.0 per cent of patients were compliant with all their medicines.
Analysis to investigate construct validity indicated that patient-related factors (age, level of education, gender, living arrangements and type of disease) did not have any effect on compliance (P>0.05); however, medicine-related factors such as increased complexity of drug regimen (increased number of medicines and dosage units per day, Mann Whitney test P<0.01) and presence of drug related problems (chi-squared P=0.04) did have an impact. At six months, there was a trend for intervention patients to be compliant with a higher percentage of medicines compared with control patients (Mann Whitney test P=0.06) and a significantly higher proportion of intervention patients were compliant with all medicines compared with control patients (intervention 46.2 per cent, control 19.1 per cent; chi-squared P=0.002). Analysis of change over time indicated that a significantly higher proportion of intervention patients remained compliant with all medicines or improved from being non-compliant to compliant compared with control patients (chi-squared P=0.02).

Discussion Despite the limitations associated with this indirect method of measuring compliance, the results presented support previous evidence of validity.2 Furthermore the results indicate that the method can identify changes in medicine-taking behaviour following pharmaceutical intervention and hence may be of use in assessing improvement in compliance as an outcome of pharmaceutical care.

The pharmacy practice research group, the school of pharmacy, The Queen's University of Belfast, 97 Lisburn Road, Belfast, Northern Ireland


1. McGavock H. A review of the literature on drug adherence. London: Royal Pharmaceutical Society, 1996.
2. Steiner JF, Prochazka AV. The assessment of refill compliance using pharmacy records: methods, validity and applications. J Clin Epidemiol 1997;50:105-116.
3.Sturgess IK, McElnay JC, Hughes CM. Community pharmacy based provision of pharmaceutical care to older patients: an international European study. Pharm J 1999;263;R8.
4. Raynor DK. Patient compliance: the pharmacist's role. Int J Pharm Prac 1992; 2:126-35.

Citation: The Pharmaceutical Journal URI: 20002889

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