Medication-Taking Habit and Outcome of Glucosamine Sulfate for Osteoarthritis Patients Influenced by National Health Insurance Regulations in Taiwan

This study compared the dosage and different medication-taking habits of glucosamine sulfate (GS) for osteoarthritis patients and evaluated the influence of the National Health Insurance (NHI) prescription guidelines. The subjects were collected from the Taiwan NHI Research Database from 1 January 2004, to 31 December 2008, and 10,501 osteoarthritis patients were included. Then, 271 patients who continuously used nonsteroidal anti-inflammatory drug (NSAIDs) and started to receive glucosamine for the first time since 2005 (no glucosamine use in 2004) were compared with 593 age-matched patients who continuously used NSAIDs but never received any glucosamine drugs from 2004 to 2008. The mean treatment duration of the glucosamine-treated and NSAID-treated groups was 40.38 ± 7.89 and 45.82 ± 3.89 months, respectively. The most common medication-taking habit was 250 mg 3 times a day for 3 months and discontinued for 3 months. It was as indicated and covered by the NHI. Only 0.7% of patients used the recommended daily dosage of 1500 mg. Patients using GS surprisingly had a higher incidence rate of joint replacement surgery than those who did not use GS. The NHI prescription guidelines may cause patient selection bias, which decreases the efficacy of GS. Moreover, patients tend to have an altered medication-taking habit, with a daily dosage of 750 mg, which is lower than the recommended therapeutic dose.