Adherence to hypertension medication: Quantitative and qualitative investigations in a rural Northern Vietnamese community.
OBJECTIVE
The purposes of this study were to assess the adherence to medication of hypertensive patients visiting community health stations in a rural area in Vietnam, to examine the relationship between levels of adherence and cardiovascular risk among hypertensive patients and to further understand factors influencing adherence.


METHODS
This study is part of a prospective one-year study conducted on hypertension management in a population aged 35 to 64 years. Data on age, sex, blood pressure and blood test results were collected at baseline. Cardiovascular risk was based on the Cardiovascular Risk Prediction Model for populations in Asia. To calculate medication adherence, the number of days the drug was taken was divided by the number of days since the first day of the prescription. A threshold of 80% was applied to differentiate between adherence and non-adherence. In-depth interviews were conducted among 18 subjects, including subjects classified as adherent and as non-adherent.


RESULTS
Among 315 patients analyzed, 49.8% of the patients were adherent. Qualitative investigation revealed discrepancies in classification of adherence and non-adherence based on quantitative analysis and interviews. No significant difference in medication compliance between two cardiovascular disease risk groups (<10% vs. >10% risk) was found, also not after controlling for age, sex, and ethnicity (adjusted odds ratio at 1.068; 95% CI: 0.614 to 1.857). The odds of medication adherence in females was 1.531 times higher than in males but the difference was not statistically significant (95% CI: 0.957 to 2.448). Each one-year increase in age resulted in patients being 1.036 times more likely to be compliant (95% CI: 1.002 to 1.072). Awareness of complications related to hypertension was given as the main reason for adherence to therapy.


CONCLUSIONS
Medication adherence rate was relatively low among hypertensive subjects. The data suggest that rather than risk profile, the factor of age should be considered for guiding the choice on who to target for improving medication adherence.
Department of Pharmacy, Unit of PharmacoTherapy, -Epidemiology & -Economics (PTE2), University of Groningen, Groningen, the Netherlands.
Thi-Phuong-Lan
TP
Nguyen
Department of Pharmacy, Unit of PharmacoTherapy, -Epidemiology & -Economics (PTE2), University of Groningen, Groningen, the Netherlands.
Catharina C M
CC
Schuiling-Veninga
Department of Health Economics, Ha Noi University of Medicine, Ha Noi, Vietnam.
Thi Bach Yen
TB
Nguyen
Thai Nguyen University of Medicine and Pharmacy, Thai Nguyen, Vietnam.
Thu-Hang
TH
Vu
Medical Committee Netherlands-Vietnam, Amsterdam, The Netherlands.
E Pamela
EP
Wright
Department of Pharmacy, Unit of PharmacoTherapy, -Epidemiology & -Economics (PTE2), University of Groningen, Groningen, the Netherlands.|Institute of Science in Healthy Aging & health caRE (SHARE), University Medical Center Groningen (UMCG), University of Groningen, Groningen, the Netherlands.|Department of Epidemiology, UMCG, University of Groningen, Groningen, the Netherlands.
Maarten J
MJ
Postma
D000328:Adult; D000959:Antihypertensive Agents / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D055118:Medication Adherence; D008875:Middle Aged; D011446:Prospective Studies; D062486:Public Health Surveillance; D036301:Qualitative Research; D012424:Rural Population; D012959:Socioeconomic Factors; D014744:Vietnam / Q000453:epidemiology
D000959:Antihypertensive Agents