JMIR Publications

ABSTRACT

Background:

As countries promote generic drug prescribing, growth may plateau at a certain usage level, warranting further investigation into the factors influencing prescribing, including physician and patient perspectives. Therefore, additional strategies may be required to maximize the switch to generic drugs with the sustainability of the healthcare system in mind, focusing on factors other than the conventional low cost. Namely, it is desirable not only to emphasize the low cost of generic drugs but also to clarify other prescription considerations.

Objective:

This study aimed to provide initial insights into how patient severity, composite adherence, and physician-patient relationships impact generic switching.

Methods:

This study utilized a long-term retrospective cohort design by analyzing data from a national healthcare database. The population included patients of all ages who required first-to-tertiary preventive actions with a history of hospitalization for cardiovascular diseases (ICD-10, I 00-99) during a four-year period from April 2014 to March 2018. The focus was on switching to generic drugs, with temporal variations in clinical parameters as explanatory variables. Lifestyle factors (smoking and drinking) were also considered. The adherence was a composite measure consisting of 11 elements. The physician–patient relationship was established based on the interval between physician change and prescription. Logistic regression analysis and propensity score matching (PSM) were employed, along with complementary analysis of physician-patient relationships, proportion of days covered (PDC), and adherence, for a subset of the population.

Results:

The study included 48,456 patients with an average follow-up of 36.1±8.8 months. The mean age was 68.3 ± 9.9 years, the body mass index was 23.4 ± 3.4 kg/m2, systolic blood pressure was 131.2 ± 15.0 mmHg, LDL-C was 116.6 ± 29.3 mg/dL, HbA1c was 5.9% ± 0.8%, and serum creatinine was 0.9 ± 0.8 mg/dL. Logistic regression analysis revealed significant associations between generic switching and systolic blood pressure (odds ratio [OR], 0.996, 95% confidence interval [CI]: 0.993–0.999), serum creatinine levels (OR, 0.838, 95% CI: 0.729–0.963), glutamic oxaloacetic transaminase levels (OR, 0.994, 95% CI: 0.990–0.998), PDC score (OR, 0.959), and adherence score (OR, 0.910). Additionally, generic drug rates increased with improvements in the HbA1c level band and smoking level. The group with a superior physician-patient relationship after PSM had a significantly higher rate of generic drug prescribing (51.6±15.2%) than the inferior relationship group (47.7±17.7%). Improved adherence scores were significantly associated with an increased PDC rate.

Conclusions:

Although physicians’ understanding influences the choice of generic drugs, patient condition (severity) and adherence impact the generic drug choice. For example, improved creatinine levels are associated with generic drug choice, while stronger physician-patient relationships correlate with higher rates of generic drug utilization. These findings may contribute to the appropriate prescription of pharmaceuticals if the policy diffusion of generic drugs begins to slow down. Thus, preventing serious illness while building trust may result in clinical benefits and positive socio-economic outcomes.