Rates and risk factors for nonadherence to the medical regimen after adult solid organ transplantation.

Background: Despite the impact of medical regimen nonadherence on health outcomes after organ transplantation, there is mixed and conflicting evidence regarding the prevalence and predictors of posttransplant nonadherence. Clinicians require precise information on nonadherence rates in order to evaluate patients' risks for this problem.

Methods: A total of 147 studies of kidney, heart, liver, pancreas/kidney-pancreas, or lung/heart-lung recipients published between 1981 and 2005 were included in a meta-analysis. Average nonadherence rates were calculated for 10 areas of the medical regimen. Correlations between nonadherence and patient psychosocial risk factors were examined.

Results: Across all types of transplantation, average nonadherence rates ranged from 1 to 4 cases per 100 patients per year (PPY) for substance use (tobacco, alcohol, illicit drugs), to 19 to 25 cases per 100 PPY for nonadherence to immunosuppressants, diet, exercise, and other healthcare requirements. Rates varied significantly by transplant type in two areas: immunosuppressant nonadherence was highest in kidney recipients (36 cases per 100 PPY vs. 7 to 15 cases in other recipients). Failure to exercise was highest in heart recipients (34 cases per 100 PPY vs. 9 to 22 cases in other recipients). Demographics, social support, and perceived health showed little correlation with nonadherence. Pretransplant substance use predicted posttransplant use.

Conclusions: The estimated nonadherence rates, overall and by transplant type, allow clinicians to gauge patient risk and target resources accordingly. Nonadherence rates in some areas--including immunosuppressant use--appear unacceptably high. Weak correlations of most patient psychosocial factors with nonadherence suggest that attention should focus on other classes of variables (e.g., provider-related and systems-level factors), which may be more influential.