10-year trajectories of pain in early knee and hip osteoarthritis; the check study

Abstract

Purpose: To determine subgroups of patients with homogenous patterns of pain over 10 years follow-up, among patients with early hip and/or knee complaints in primary care. Next, baseline demographics and number total joint replacements over time will be compared between groups. Methods: Data from the CHECK cohort (Cohort Hip and Cohort Knee) were used. For this cohort, 1002 patients between 45 and 65 years at or within 6 months from their first consultation at a general practitioner for symptoms of their hips and/or knees, not explained by other diseases, were included and followed for 10 years. A numeric rating scale (NRS) for perceived pain was obtained at baseline and after 2, 5, 8 and 10 years, or until total joint replacement. Using these longitudinal data, subgroups of patients with comparable trajectories over time were identified using Latent Class Growth Analysis (LCGA). Models with 3–6 classes when using linear, cubic and quadratic trajectories were evaluated using Mplus software. Results: At baseline, the 998 subjects (79% women) with ≥2 NRS data points available had a mean age of 55.9 ± 5.2 years and a mean BMI of 26.2 ± 4.0 kg/m2. In total, 410 patients reported knee pain only (41%), 173 hip pain only (17%), and 415 reported both knee and hip pain (42%) at baseline. On a joint level, 156 knees and 160 hips had KL-grade ≥ 2 at baseline. The by LCGA derived models of 3 groups with a linear trajectory and of 6 groups with a cubic trajectory resulted in comparable goodness of fit indicators (Bayesian Information Criteria 17991 vs. 17927, Akaike Information Criteria 17927 vs. 17761, and entropy 0.694 vs. 0.683 for the 3 and 6 group models, respectively). Both models and the corresponding trajectories are presented in the Figure. Clinical characteristics and number of total joint replacements over time for each of the groups are presented in the Table. In the 3 group model, the ‘high pain trajectory’ (group 2, blue line) had the highest percentage of patients with knee and hip complaints, females, total joint replacements, and the highest mean BMI. The ‘low pain trajectory’ (group 3, green line) had the highest percentage of patients with only hip and only knee complaints, and the lowest mean BMI. In the 6 group model, the ‘always high pain trajectory’ (group 1, red line) had the highest percentage of females and total joint replacements (knees more pronounced than hips), and the highest mean BMI. The ‘always low pain trajectory’ (group 5, brown line) had the highest percentage of patients with only knee complaints and the lowest mean BMI. The ‘decreasing pain trajectory’ (group 2, blue line) had the highest percentage of patients with only hip complaints. The ‘fluctuating high pain trajectories’ (groups 3 and 4, green and pink lines) had the highest percentage of females and patients with knee and hip complaints. Conclusions: The 6 group model identified more extreme groups with lower minimal and higher maximal prevalence of the presented clinical characteristics. In the end, the conclusion drawn from the two models appear similar; Patients presenting with both knee and hip complaints had less favorable pain trajectories over the following 10 years and the number of total joint replacements was the highest in the groups always reporting high pain scores.TableClinical characteristics and number of total joint replacements for two modelsModelGroup (line colour in Figure)NKnee pain onlyHip pain onlyKnee and hip pain% femalesBMI (kg/m2)TKP during follow-upTHP during follow-up3 groups with a linear trajectoryGroup 1 (red)351130 (37%)60 (17%)161 (46%)82%26.4 ± 3.915 (4%)28 (8%)Group 2206682811084%27.6 ± 4.61529(blue)(33%)(14%)(53%)(7%)(14%)Group 34412128514475%25.3 ± 3.6417(green)(48%)(19%)(33%)(1%)(4%)6 groups with a cubic trajectoryGroup 117656299186%27.7 ± 4.71231(red)(32%)(17%)(52%)(7%)(18%)Group 2371581470%26.1 ± 3.402(blue)(41%)(22%)(38%)(0%)(5%)Group 3882595483%26.3 ± 4.258(green)(28%)(10%)(61%)(6%)(9%)Group 414260196386%26.5 ± 4.187(pink)(42%)(13%)(44%)(6%)(5%)Group 5289146618271%25.0 ± 3.4112(brown)(51%)(21%)(28%)(0%)(4%)Group 62661084711179%26.2 ± 3.8814(yellow)(41%)(18%)(42%)(3%)(5%) Open table in a new tab