Impact of the socioeconomic status on the probability of receiving formulary restricted thiazolidine (TZDs).

BACKGROUND

In the province of Quebec, Canada, the reimbursement of thiazolidinediones (TZDs) is limited to patients who do not respond to doses of metformin and a sulfonylurea.

OBJECTIVES

The objective of this research project was to study, in a real-life setting, the ârisk factorsâ for receiving these restricted drugs among patients who meet the reimbursement criteria.

METHODS

Among patients eligible for drug coverage under the RAMQ between May 2000 and June 2005, we selected those who received six consecutive dispensations of high doses of both metformin and a sulfonylurea. The date of the sixth dispensation was set as the index date. The proportion of patients who received a TZD in the year following the index date was calculated and a logistic regression was used to estimate the impact of several factors on the probability of receiving a TZD.

RESULTS

There were 4,836 patients in the cohort. A TZD was dispensed to 24.9% (95% CI: 23.7%;26.2%) of the patients. Compared to the oldest group of patients (65 years and more), the probability to receive a TZD was higher for patients aged 51 to 64 years (OR=1.33 95% CI: 1.11;1.59) and patients aged 19 to 50 years [OR=1.81 (95% CI: 1.40;2.33)]. Patients with the highest income were more likely to receive a TZD (OR=1.55 95% CI: 1.21;1.98) compared to patients with the lowest income.

CONCLUSIONS

These findings suggest that the restricted access to TZDs probably results in social inequities, as individuals with lower incomes are less likely to receive these drugs. Key words: Restricted drugs, TZDs, diabetes.