Evaluation of drug usage and expenditure in a hospital diabetes clinic.

BACKGROUND

Diabetes mellitus is a major public health problem and often coexists with hypertension and dyslipidaemia. A prescription-based survey was conducted to examine the use of antidiabetic, antihypertensive and lipid lowering drugs in a hospital diabetes clinic. The expenditure incurred was also evaluated.

METHOD

Prescriptions issued from the diabetes clinic were collected for 4 consecutive weeks. Drugs were categorized into three main classes--antidiabetic, antihypertensive and lipid-lowering drugs. The unit cost of each drug and the total amount prescribed were used to estimate the total drug costs.

RESULTS

During the 4-week study period, 534 prescriptions were collected, of which 520 contained antidiabetic drugs. Oral hypoglycaemic agents were prescribed in 379 patients (72.9%). Sulphonylurea was used as a single agent in 119 (22.9%) patients, in combination with metformin in 219 (42%) patients and with insulin in 17 patients (3.3%). Among patients treated with sulphonylureas (n=342), glibenclamide (47.7%) and gliclazide (30.7%) were the main drugs prescribed. Metformin monotherapy was prescribed in only 31 patients (6%). Insulin treatment was prescribed in 141 (27%) patients and in combination with oral drugs in 23 patients (4.5%). Of the 534 prescriptions, 225 (42%) contained antihypertensive drugs. Calcium channel blocking agents and angiotensin converting enzyme inhibitors were the most commonly prescribed drugs in both monotherapy (n=155) and combination therapy (n=70). The antidiabetic and antihypertensive drugs accounted for 45% and 39% of the total drug expenditure, respectively. Lipid-lowering drugs were prescribed in 8% of the diabetic patients. Simvastatin and gemfibrozil were the most common drugs prescribed and accounted for 12% of the total drug expenditure.

CONCLUSION

The use of antidiabetic drugs represents a major burden on the health care system. The high proportions of patients requiring antihypertensive drugs and lipid lowering drugs further increase drug expenditure. Most of these treatments have been shown to improve clinical outcomes and quality of life, if used appropriately. The impacts of these long-term medications on health care financing require careful evaluation to assess their cost-effectiveness.