The cross-sectional study examined how the influence of cost sharing on adherence to antihypertensive drugs varies across adherence levels. The researchers selected hypertension as one of the most prevalent chronic condition in the United States. In relation to the study, it utilized claims data from employer-sponsored health plans for a large sample of working age adults diagnosed with hypertension. The results of the study showed that cost sharing had a significant negative relationship with adherence for low adherers and little association for high adherers.
Factors such as co morbidity and drug class resulted to low adherence of hypertensive patients. Thus, the study strongly recommended that current benefit designs of the health care system should encourage adherence while restricting the financial burden for patients with co morbidity or multiple chronic conditions taking several drugs. The nonparametric test was used to determine the bivariate difference in the median medication possession ratio (MPR) by patient and health plan characteristics on a period of over nine months.
The method is appropriate for the study as its data have ranking but no clear numerical interpretation. The dependent variable of the study is the adherence to anti-hypertensive drugs. The level of measurement was through the medication possession ratio (MPR) that represents the amount of time for which the patient had his or her drug supply that varied from 0% to more than 100% for patients who had overlapping prescriptions.
The independent variable studied is the influence of cost sharing, drug class and co-morbidity or termed as the main covariates. The measurements of patient cost sharing for drugs was categorized into less than $5 copayment per prescription, $6 to $ 12 copayment, more or less $15 copayment, 10% insurance, or 20% coinsurance. Co-morbidity was measured using morbidity groupings from ICD-9 codes in medical claims termed as aggregated diagnosis groups. A statistically significant level at the 0.05 level means that there is one in twenty chance that the findings was accidental.
When findings are correlated based on their statistical significance, it is known that the findings, except for gender, were statistically significant at a probability of zero. In conclusion, cost sharing and adherence to antihypertensive drugs have little association. Patients were found out to have less drug compliance due to co-morbidity, presence of side effects from drugs, and cost burden of drugs.