Nine relevant studies were identified. The number of analyzed patients ranged between 12 and 5706 patients. The study quality was moderate. Especially the risk of bias regarding the measurement of influencing factors was mostly unclear.”Psychiatric disorders” (N = 5) and having to take “higher doses of ribavirin” (N = 3) showed a negative influence on adherence. In contrast, a “HIV co-infection” (N = 2) and the “hemoglobin level” (N = 2) were associated with a positive influence on adherence. Furthermore, there is the tendency that male patients are more adherent than female patients (N = 6). “Alcohol consumption” (N = 2), “education”, “employment status”, “ethnic group”,”hepatitis-C virus RNA” (N = 4), “genotype” (N = 5), “metavir activity” (N = 1) and “weight” (N = 3) showed mostly no effect on adherence. Although, some studies showed statistically significant results for “age”, “drug use” , “genotype”, “medication dose interferon”, and “treatment experience” the effect is unclear because effect directions were partly conflicting.The other factors were heterogeneous regarding the effect direction and/or statistical significance.
CONCLUSION:
There are some factors that seem to show an influence on adherence. However, due to the heterogeneity (e.g. patient characteristics, regimes, settings, countries) no general conclusions can be made. The results should rather be considered as indications for factors that can have an influence on adherence in hepatitis-C infected patients taking regimes that containing ribavirin.