Faculty of Pharmacy, The University of Sydney, Camperdown, Sydney, Australia.
BMC Musculoskelet Disord. 2013 May 6;14:160. doi: 10.1186/1471-2474-14-160.
Often affecting knee joints, osteoarthritis (OA) is the most common type of arthritis and by 2020 is predicted to become the fourth leading cause of disability globally. Without cure, medication management is symptomatic, mostly with simple analgesics such as acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), and glucosamine sulfate. Adherence to arthritis medications is generally low. Intentional non-adherence, that is deliberate decision-making about the use of analgesics, occurs in OA patients. To date, a limited number of studies have explored medication-taking decisions in people with OA nor the extent to which individuals' trade off one treatment factor for another in their decision-making using quantitative techniques. This study aimed to estimate the relative influence of medication-related factors and respondent characteristics on decisions to continue medications among people with symptomatic OA.
A discrete choice experiment (DCE) was conducted among participants attending end-of-study visits in the Long-term Evaluation of Glucosamine Sulfate (LEGS) study (ClinicalTrials.gov ID: NCT00513422). The paper-based survey was used to estimate the relative importance of seven medication specific factors (pain efficacy, mode of action, dose frequency, treatment schedule, side effects, prescription, and out-of-pocket costs) and respondent characteristics on decisions to continue medications.
188 (response rate 37%) completed surveys were returned. Four of the seven medication factors (side effects, out-of-pocket costs, mode of action, treatment schedule) had a significant effect on the choice to continue medication; patient characteristics did not. Assuming equivalent pain efficacy and disease-modifying properties for glucosamine, the positive relative likelihood of continuing with sustained-release acetaminophen was equivalent to glucosamine. By contrast, the negative relative likelihood of NSAID continuation was mostly driven by the side effect profile. The predicted probability of continuing with glucosamine decreased with increasing out-of-pocket costs.
This study has characterised the complexity of medication-taking decisions that potentially underpin intentional non-adherent behaviour for people with symptomatic OA. In particular, medication risks and cost were important and ought to be borne into considerations in interpreting clinical trial evidence for practice. Ultimately addressing these factors may be the way forward to realising the full potential of health and economic benefits from the efficacious and safe use of OA medications.
骨关节炎（OA）常影响膝关节，是最常见的关节炎类型，预计到 2020 年将成为全球第四大致残原因。由于无法治愈，药物治疗主要是对症治疗，多采用对乙酰氨基酚和非甾体抗炎药（NSAIDs）等简单镇痛药以及硫酸氨基葡萄糖。关节炎药物的依从性一般较低。OA 患者存在故意不依从，即故意决定使用镇痛药。迄今为止，只有少数研究探讨了 OA 患者的用药决策，也没有使用定量技术研究个体在决策中如何权衡一种治疗因素与另一种治疗因素。本研究旨在评估与药物相关的因素和受访者特征对有症状 OA 患者继续用药决策的相对影响。
在长期硫酸氨基葡萄糖评价（LEGS）研究的结束访视中进行了离散选择实验（DCE）（ClinicalTrials.gov ID：NCT00513422）。该纸质调查用于估计七种药物特定因素（疼痛疗效、作用机制、剂量频率、治疗方案、副作用、处方和自付费用）和受访者特征对继续用药决策的相对重要性。
共收回 188 份（应答率 37%）完成的调查问卷。七种药物因素中的四种（副作用、自付费用、作用机制、治疗方案）对继续用药的选择有显著影响；患者特征没有。假设氨基葡萄糖的疼痛疗效和疾病修饰特性相当，持续释放对乙酰氨基酚继续使用的相对可能性等同于氨基葡萄糖。相比之下，NSAID 继续使用的负相对可能性主要是由副作用特征驱动的。继续使用氨基葡萄糖的预测概率随着自付费用的增加而降低。
本研究描述了有症状 OA 患者有意不依从行为潜在的用药决策复杂性。特别是，药物风险和成本很重要，在解释临床研究证据以指导实践时应当予以考虑。最终解决这些因素可能是充分发挥 OA 药物有效和安全使用带来的健康和经济效益的途径。
