Factors associated with osteoporosis treatment adherence in Hong Kong

Abstract

Introduction: Effective prevention of osteoporotic fracture requires long term adherence to osteoporosis medication. Longitudinal studies revealed that more than 60% of patients terminated their treatment at one year and the problem increases with time. The problem of non-adherence to osteoporosis medication in Hong Kong is unclear. Objective: To assess patient adherence to osteoporosis medication in Hong Kong and to identify the associating factors for nonadherence. Method: 244 patients attended the osteoporosis clinic in Queen Mary Hospital for the first time between January 2007 and December 2008 were invited to participate in a retrospective observational study for their adherence to treatment. Baseline clinical and demographic information, bone mineral density, lifestyle risk factors were assessed by medical charts review. Details in treatment adherence, acceptance, incident fractures, hospital admission and mobility level were collected by telephone interviews. Information were verified from the Hospital Authority Electronic Patient Record System. Medication compliance was measured by proportion of days covered (PDC). A patient is considered as a complier if he/she had missed < 20% of the proportion of days covered (PDC). Results: A total of 193 patients participated in this study with 79.1 % response rate. The mean rate of medication adherence was 75.3% (PDC) after a mean follow up of 2.3 years. The rate of medication adherence decreased progressively with follow up duration (PDC: 74.5% at first year, 75.6% at second year, 63.7% at third year). The risk factors for non-adherence to treatment were self-perceived having too many medications (OR: 19.77, 95% CI: 2.41-161.99, p<0.001); self-perceived adverse effect from medication (OR: 16.98, 95% CI: 2.04-141.35, p=0.001); self-perceived cannot afford the medication (OR: 14.29, 95% CI: 1.68-121.5, p=0.004); self-perceived not requiring the medication (OR: 9.53, 95% CI: 2.99-30.42, p <0.001); bedbound (OR: 9.19, 95% CI: 1.00-84.08, p=0.035); smoking (OR: 3.97, 95% CI: 1.23-12.76, p=0.025); unsatisfied with medication (OR: 3.17, 95% CI: 1.05-9.59, p=0.04) and medication adverse effect (OR: 1.15, 95% CI: 1.04-1.27, p<0.001). Conclusion: Although the rate of non-adherence in our study was lower than reported by overseas studies, the problem exacerbated with longer treatment duration. Several self-perceived factors were found associated with patient non-adherence. This study identified the common misconceptions and concerns about osteoporosis medications among patients that required long term treatment. To lower the non-adherence rate, doctors should improve their communications with patients to resolve their concerns with long term medical therapy.