All-cause mortality and serious cardiovascular events in people with hip and knee osteoarthritis: a population based cohort study

BACKGROUND: Because individuals with osteoarthritis (OA) avoid physical activities that exacerbate symptoms, potentially increasing risk for cardiovascular disease (CVD) and death, we assessed the relationship between OA disability and these outcomes. METHODS: In a population cohort aged 55+ years with at least moderately severe symptomatic hip and/or knee OA, OA disability (Western Ontario McMaster Universities (WOMAC) OA scores; Health Assessment Questionnaire (HAQ) walking score; use of walking aids) and other covariates were assessed by questionnaire. Survey data were linked to health administrative data to determine the relationship between baseline OA symptom severity to all-cause mortality and occurrence of a composite CVD outcome (acute myocardial infarction, coronary revascularization, heart failure, stroke or transient ischemic attack) over a median follow-up of 13.2 and 9.2 years, respectively. RESULTS: Of 2156 participants, 1,236 (57.3%) died and 822 (38.1%) experienced a CVD outcome during follow-up. Higher (worse) baseline WOMAC function scores and walking disability were independently associated with a higher all-cause mortality (adjusted hazard ratio, aHR, per 10-point increase in WOMAC function score 1.04, 95% confidence interval, CI 1.01–1.07, p = 0.004; aHR per unit increase in HAQ walking score 1.30, 95% CI 1.22–1.39, p<0.001; and aHR for those using versus not using a walking aid 1.51, 95% CI 1.34–1.70, p<0.001). In survival analysis, censoring on death, risk of our composite CVD outcome was also significantly and independently associated with greater baseline walking disability ((aHR for use of a walking aid  = 1.27, 95% CI 1.10–1.47, p = 0.001; aHR per unit increase in HAQ walking score  = 1.17, 95% CI 1.08–1.27, p<0.001). CONCLUSIONS: Among individuals with hip and/or knee OA, severity of OA disability was associated with a significant increase in all-cause mortality and serious CVD events after controlling for multiple confounders. Research is needed to elucidate modifiable mechanisms

Understanding the pain experience in hip and knee osteoarthritis – an OARSI/OMERACT initiative

SummaryObjectiveTo examine the pain experience of people with hip or knee osteoarthritis (OA), particularly changes over time and most distressing features.MethodFocus groups in individuals aged 40+ years with painful hip or knee OA obtained detailed descriptions of OA pain from early to late disease. A modified Patient Generated Index (PGI) was used to assess the features of OA pain that participants found most distressing. Content analysis was performed to examine response patterns; descriptive statistics were used to summarize PGI responses.ResultsMean age of the 143 participants (52 hip OA; 91 knee OA) was 69.5 years (47–92 years); 60.8% were female and 93.7% Caucasian. Participants described two distinct types of pain – a dull, aching pain, which became more constant over time, punctuated increasingly with short episodes of a more intense, often unpredictable, emotionally draining pain. The latter, but not the former, resulted in significant avoidance of social and recreational activities. From PGI responses, distressing pain features were: the pain itself (particularly intense and unpredictable pain) and the pain's impact on mobility, mood and sleep.ConclusionsTwo distinct pain types were identified. Intermittent intense pain, particularly when unpredictable, had the greatest impact on quality of life

The development of a short measure of physical function for knee OA KOOS-Physical Function Shortform (KOOS-PS) – an OARSI/OMERACT initiative

SummaryObjectiveTo develop a short measure of physical function for knee osteoarthritis (OA) using multi-national data from individuals with varying degrees of severity of knee OA.MethodsRasch analysis, based on the partial credit model, was conducted on Knee injury and Osteoarthritis Outcome Score and Western Ontario McMaster Universities' Osteoarthritis Index data from individuals with knee OA, ranging from community to pre-total knee replacement samples from five countries. Fit of the data to the Rasch model was evaluated by overall model fit and item-level fit statistics (χ2, size of residual, F-test). Invariance across age, gender and country was evaluated. Unidimensionality was evaluated by factor analysis of residuals. The derived short measure was further tested for fit through re-analyses in individual sub-samples. A nomogram converting raw summed scores to Rasch-derived interval scores was developed.ResultsThirteen data sets were included (n=2145), with an age range of 26–95 years, and a male/female ratio of 1:1.4. The final model included seven of the original 22 items. From easiest to most difficult, the items (logit) were as follows: rising from bed (1.366), putting on socks/stockings (1.109), rising from sitting (0.537), bending to the floor (0.433), twisting/pivoting on injured knee (−0.861), kneeling (−1.292) and squatting (−1.292). Sub-sample analyses confirmed findings.ConclusionBased on the use of accepted Rasch-based measurement methods and the compliment of countries, languages and OA severity represented in this study, our seven item short measure of physical function for knee OA is likely generalizable and widely applicable. This measure has potential for use as the function component in an OA severity scoring system

Development of a population-based microsimulation model of osteoarthritis in Canada

OBJECTIVES: The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN: We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS: Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS: We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature

Comparative evaluation of three semi-quantitative radiographic grading techniques for hip osteoarthritis in terms of validity and reproducibility in 1404 radiographs: report of the OARSI-OMERACT Task Force

OBJECTIVE: The objective of this work was to compare the measurement properties of three categorical X-ray scoring methods for hip osteoarthritis (OA). METHODS: In data obtained from trials and cohorts, radiographs were evaluated using the Kellgren and Lawrence (KL) grading system, the Osteoarthritis Research Society International (OARSI) joint space narrowing score, and quantitative measurement of joint space width (JSW), analysed as a categorical variable according to Croft and Lane's cutoffs (1.5, 2.5 and 3mm). Predictive validity was assessed through logistic regression to predict joint replacement in one database. Construct validity was assessed through logistic regression between pain and function and X-ray stages. Inter-observer and intra-observer reliability were assessed in 50 subjects by weighted kappa. Sensitivity to change was assessed in 50 patients over a 24-month interval, by standardized response mean (SRM). RESULTS: Radiographs were available from one trial and two cohorts (1404 X-rays). All three methods predicted joint replacement in the trial. Correlation with clinical parameters was low for the three scoring methods, except for the single community-based cohort. Interrater reliability was higher for categorical JSW (kappa, 0.71 vs 0.44 and 0.47 for KL and OARSI, respectively). Intrarater reliability was similar for the three methods (0.79 vs 0.69 and 0.81). Sensitivity to change was higher for categorical JSW than KL and OARSI (SRM, 0.77 vs 0.28 and 0.35). CONCLUSION: Categorical JSW has similar validity and higher sensitivity to change than the other categorical scoring techniques in hip OA. These results indicate categorical JSW may be the preferred method to evaluate structural severity in hip OA clinical trials