Greater efficacy of a combination of conservative therapies for thumb base OA in individuals with lower radial subluxation - a pre-planned subgroup analysis of the COMBO trial.

OBJECTIVE: To investigate heterogeneous effects of a combination of conservative therapies compared with an education comparator for thumb base (TB) osteoarthritis (OA) according to clinically relevant characteristics. METHODS: Pre-planned subgroup analysis of the COMBO trial (n = 204) which compared a combination of education on self-management and ergonomic principles, a prefabricated neoprene splint, hand exercises, and diclofenac sodium gel, with education alone for radiographic and symptomatic TB OA. Primary outcomes were change in pain (visual analogue scale [VAS], 0-100 mm) and hand function (Functional Index for Hand Osteoarthritis questionnaire, 0-30) from baseline to week-6. Other outcomes were grip and tip-pinch strength and patient's global assessment (PGA) (VAS, 0-100 mm). Possible treatment effect modifiers were the presence of interphalangeal joint pain, erosive hand OA, radiographic thumb carpometacarpal joint subluxation (higher vs equal or lower than the sample mean), and baseline radiographic OA severity (Kellgren Lawrence grade). Linear regression models were fitted, adding interaction terms for each subgroup of interest. RESULTS: The treatment effects of the combined intervention at 6 weeks were greater in participants with lower joint subluxation compared with those with greater subluxation (pain -11.6 [95%CI -22.2, -9.9] and 2.6 [-5.5, 10.7], respectively, difference between the subluxation groups 14.2 units (95% CI 2.3, 26.1), p-value 0.02; and PGA -14.0 [-22.4, -5.5] and 1.5 [-6.2, 9.3), respectively, difference between the subluxation groups 15.5 units (95% CI 4.2, 26.8), p-value 0.03). There was no statistically significant heterogeneity for the other subgroups. CONCLUSION: A combination of conservative therapies may provide greater benefits over 6 weeks in individuals with lower joint subluxation, although the clinical relevance is uncertain given the wide confidence intervals. Treatment strategies may need to be customized for those with greater joint subluxation. TRIAL REGISTRATION NUMBER: ACTRN 12616000353493.

Association of weather factors with the risk of pain exacerbations in people with hip osteoarthritis.

Objectives: Our objective was to evaluate the association of weather factors with the risk of pain exacerbations in people with symptomatic hip osteoarthritis (OA). Method: Eligible participants with symptomatic hip OA were instructed to log on to the study website and complete questionnaires every 10 days and additionally whenever they considered they were experiencing a pain exacerbation (case period) during the 90 day follow-up. Pain exacerbation was defined as an increase of two points in pain intensity on an 11-point numeric rating scale (0-10) during the follow-up compared with baseline. Each case period was anchored to four control periods within a 35 day interval using a time-stratified approach. Weather data were obtained for both periods from the publicly available meteorological database of the Australian Bureau of Meteorology. We examined the association of weather factors across 72 h before the index date with the risk of pain exacerbation, using conditional logistic regression. Results: Among 252 participants recruited, 129 participants had at least one episode of pain exacerbation and were included in the analysis. A significant dose-response relationship was found between average daily temperature variation in the prior 72 h and risk of pain exacerbations (p = 0.04 for linear trend). There was no significant association between maximum daily temperature, minimum daily temperature, relative humidity, precipitation, or barometric pressure and hip pain exacerbations. Conclusion: The overall results suggest that only daily temperature variation among different weather factors was associated with hip pain exacerbations in people with symptomatic hip OA.

Is the Patient Activation Measure a valid measure of osteoarthritis self-management attitudes and capabilities? Results of a Rasch analysis.

BACKGROUND: The Patient Activation Measure (PAM-13) was developed using Rasch analysis to assess knowledge, skills and confidence in the management of one's health. Previous studies report positive relationships between PAM-13 scores, self-management behaviours and longitudinal health outcomes in adults with chronic disease. There is little extant measurement property evidence for the use of PAM-13 in specific osteoarthritis (OA) populations. This study tested measurement properties of the PAM-13 in people living with hip and knee OA. METHODS: Item response frequency analysis was conducted. Rasch analysis evaluated the fit of the PAM-13 data to the Rasch model. Model-data fit was evaluated using infit and outfit statistics; person/item reliability and person separation indices were computed. Unidimensionality was evaluated using Principal Components Analysis of Rasch residuals and the data were assessed for item redundancy. Differential Item Functioning (DIF) examined bias in respondent subgroups and correlations tested relationships between PAM-13 and other patient-reported outcomes. RESULTS: Two-hundred-and-seventeen PAM-13 surveys were completed; there were no missing responses, floor or ceiling effects. Person and item reliability were acceptable (0.98 and 0.87 respectively) with good separation (person separation index 2.58). Unidimensionality was evaluated, with 49.4% of the variance explained by the first eigenvector. There was evidence of potential local response-dependence. The Rasch fit statistics were acceptable (except for item-2). There were some issues identified with targeting of the PAM-13 items to people with higher ability and the item difficulty order was different to that proposed in original cohorts. Significant DIF was identified for sex and educational level for a small number of items. PAM-13 scores were moderately correlated with depressive symptoms on the Depression Anxiety Stress Scale and Assessment of Quality of Life-6D. There were small correlations between PAM-13 and Knee injury and Osteoarthritis Outcome Score pain and activities of daily living scores. CONCLUSIONS: This study provides some evidence of adequate person and item reliability, unidimensionality, and construct validity to support the use of PAM-13 to measure patient activation in people living with hip and knee OA. Possible limitations regarding targeting, different item difficulty order, DIF and local response dependence should be investigated in future research.

Effect of cane use on bone marrow lesion volume in people with medial tibiofemoral knee osteoarthritis: randomized clinical trial.

OBJECTIVE: To evaluate effects of daily cane use for 3 months on medial tibiofemoral bone marrow lesion (BML) volumes in people with medial tibiofemoral osteoarthritis (OA). DESIGN: In this randomized controlled trial (RCT), 79 participants with medial tibiofemoral OA were randomized to either a cane group (using a cane whenever walking) or control group (not using any gait aid) for 3 months. The cane group received a single training session by a physiotherapist, using a biofeedback cane to teach optimal technique and body weight support and motor learning principles to facilitate retention of learning. The primary outcome was change in total medial tibiofemoral BML volume (per unit bone volume) measured from magnetic resonance imaging (MRI) at 3 months. Secondary outcomes were BML volumes (per unit bone volume) of the medial tibia and femur, and patient-reported outcomes of overall knee pain, knee pain on walking, physical function, perceived global symptom changes and health-related quality of life. MRI analyses were performed by a blinded assessor. RESULTS: Seventy-eight participants (99%) completed the primary outcome. Mean (standard deviation) daily cane use was 2.3 (1.7) hours over 3 months. No evidence of between-group differences was found for change in total medial tibiofemoral BML volume (mean difference: -0.0010 (95% confidence intervals: -0.0022, 0.0003)). Most secondary outcomes showed minimal differences between groups. CONCLUSION: Daily use of a cane during walking for 3 months aiming to reduce knee joint loading did not change medial tibiofemoral BML volumes compared to no use of gait aids. CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry (ACTRN12614000909628).