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Adherence to chronic medication in Dutch primary care.

Dijk, L. van, Somai, D., Heerdink, E., Dulmen, S. van, Sluijs, E., Ridder, D. de, Bensing, J. Adherence to chronic medication in Dutch primary care. Pharmacoepidemiology and Drug Safety: 2006, 15(suppl. 1) S200. Abstract. 22nd International Conference of Pharmacoepidemiology and Therapeutic Risk Management, Lissabon (Portugal), on 24-27 august 2006.
Background: Non-adherence is a major public health problem. Despite the large amount of research in this area there is still need for research on determinants of non-adherente. For example, the influence of prescribers on adherence in their patient population is not clear. Objectives: 1) To identify risk profiles for non-adherence to oral antidiabetics, antihypertensives and antidepressants from patients' socio-demographic characteristics, frequency of GP consultation, and use of comedication 2) To explore variation in adherence rates between general practices.Methods: Data were obtained by linkage of a general practice to a dispensing database in 2001. We identified 3548 users for oral antidiabetics, 20004 for antihypertensives,and 7365 for antidepressants listed in 79 general practices. Adherence was defined as nuinber of days for which the drug was dispensed divided by number of days between start and theoretical end date in users with 3+ prescriptions. Compliance <80% was defined as non-adherence. Data were analyzed using multilevel models. Results: 7.2% af users of oral antidiabetics with 3+ prescriptions was non-adherent. For antihypertensives and antidepressant percentages were 11.9% and 25.4%. No correlates were found for adherence to antidiabetics. Native Dutch patients were more often adherent to antihypei-tensives (OR = 1.6) and antidepressants (OR=2.1) than nonwestern immigrants. Type of inedication and complexity of medication regime were also correlated with adherence to these two drug groups. The proposition of adherent patients varied across genera1 practices: for antidiabetics the range was 42%, for antihypertensives 31%, for antidepressants 32%. This variation cannot be explained by differences in patient population. Moreover, general practices with a high proportion of adherent patients for one drug had higher proportions of adherent patients for the other drugs. Conclusions: We did not find clear risk profiles for nonadherence at the patient level. Our results show that risk profiles should include information on the patient's care provider. Future research should provide more insight into GP characteristics (f.e. cornmunication style) associated with their patients' adherence. (aut.ref.)