Determinants of diabetes-attributable non-blood glucose-lowering medication costs in type 2 diabetes: the Fremantle Diabetes Study.
OBJECTIVE
To prospectively examine the magnitude and predictors of diabetes-attributable non-blood glucose-lowering (non-BGL) medication costs in type 2 diabetes.


METHODS
Detailed data from 593 community-dwelling patients were available over 4.3 +/- 0.4 years. Diabetes-attributable costs (in year 2000 Australian dollars [A$]) were calculated by applying a range of attributable proportions for each complication for which medication was prescribed.


RESULTS
Non-BGL medications accounted for 75% of all prescription medication costs over the study period, and one-third were attributable to diabetes. The median annual cost (in A$) of non-BGL medications per patient increased from A$220 to A$429 over 4 years (P < 0.001), whereas the diabetes-attributable contribution increased from A$31 (range 15-40) to A$159 (range 95-219) per patient (P < 0.001). Diabetes-attributable hospital costs remained stable during the study. Diabetes-attributable non-BGL costs were skewed and, therefore, square root transformed before regression analysis. Independent baseline determinants of square root cost/year were coronary heart disease, systolic blood pressure, total serum cholesterol, ln(serum triglycerides), ln(albumin-to-creatinine ratio), serum creatinine, education, and, negatively, male sex and fasting plasma glucose (P </= 0.043; R(2) = 29%). Projected to the Australian population, diabetes-attributable non-BGL medication costs for patients with type 2 diabetes totaled A$79 million/year.


CONCLUSIONS
The median annual cost of diabetes-attributable non-BGL medications increased fivefold over 4 years. This increase was predicted by vascular risk factors and complications at baseline. Better-educated patients had higher costs, probably reflecting improved health care access. Men and patients with higher fasting plasma glucose levels had lower costs, suggesting barriers to health care and/or poor self-care. The contemporaneous containment of hospital costs may be due to the beneficial effect of increased medication use.
Davis
Wendy A
WA
University of Western Australia, School of Medicine and Pharmacology, Fremantle Hospital, Fremantle, Western Australia 6959. wdavis@cyllene.uwa.edu.au
Knuiman
Matthew W
MW
Hendrie
Delia
D
Davis
Timothy M E
TM
D000368:Aged; D001786:Blood Glucose / Q000187:drug effects; D048909:Diabetes Complications / Q000188:drug therapy* / Q000191:economics* / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000191:economics* / Q000453:epidemiology; D016527:Drug Costs; D011307:Drug Prescriptions / Q000191:economics* / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007004:Hypoglycemic Agents / Q000191:economics / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D014904:Western Australia / Q000453:epidemiology
D001786:Blood Glucose; D007004:Hypoglycemic Agents