Objective: To examine the effects of purchasing volume, purchasing group size, history of contracts, delivery rates, and drug types on the bargaining power of drug-purchasing groups in Thailand.
Material and Methods: A bargaining model between drug-purchasing groups and sellers was estimated by using national databases, which included drug price information and hospital information for the year 2002. Diclofenac sodium, 75 milligrams/ 3 milliliters for injection; Cefazolin, 1 gram for injection; Chloramphenicol eye drop, 0.5%; Hyoscin-N-butylbromide, 10 milligrams; Colchicine, 0.6 milligram; Ceftriaxone, 1 gram for injection: were chosen to represent drugs for treating acute disease. Enalapril, 5 and 20 milligram; Nifedipine, 10 milligram; Gemfibrozil, 300 milligrams; Salbutamol oral inhaler, 200 doses: represented drugs for treating chronic disease in this study. Ordinary least-squares regression analysis was used for estimating coefficients in the bargaining model.
Results: Only purchasing volume and drug type were significantly associated with the bargaining power of drug-purchasing groups. When the purchasing volume increased, the bargaining power of the drug-purchasing group increased. Also, the bargaining power of the drug-purchasing group significantly increased when the drugs for chronic disease were purchased. The purchasing group size, the history of contract and the delivery rate were not statistically significant factors.
Conclusion: The most important factors affecting the bargaining power of drug-purchasing groups were the purchasing volume and drug type. An increase in the purchasing group size might not significantly increase the bargaining power of the drugpurchasing groups.