Predicting OA progression to total hip replacement: can we do better than risk factors alone using active shape modelling as an imaging biomarker?

OBJECTIVE: Previously, active shape modelling (ASM) of the proximal femur was shown to identify those individuals at highest risk of developing radiographic OA. Here we determine whether ASM predicts the need for total hip replacement (THR) independent of Kellgren-Lawrence grade (KLG) and other known risk factors. METHODS: A retrospective cohort study of 141 subjects consulting primary care with new hip pain was conducted. Pelvic radiographs taken on recruitment were assessed for KLG, centre-edge angle, acetabular depth and femoral head migration. Clinical factors (duration of pain, use of a stick and physical function) were collected by self-completed questionnaires. ASM differences between shape mode scores at baseline for individuals who underwent THR during the 5-year follow-up (n = 27) and those whose OA did not progress radiographically (n = 75) were compared. RESULTS: A 1 s.d. reduction in baseline ASM mode 2 score was associated with an 81% reduction in odds of THR (OR = 0.19, 95% CI 0.52, 0.70) after adjustment for KLG, radiographic and clinical factors. A similar reduction in odds of THR was associated with a 1 s.d. reduction in mode 3 (OR = 0.45, 95% CI 0.28, 0.71) and a 1 s.d. increase in mode 4 score (OR = 2.8, 95% CI 1.7, 4.7), although these associations were no longer significant after adjustment for KLG and clinical factors. CONCLUSION: ASM of the hip joint is a reliable early biomarker of radiographic OA severity, which can improve the ability to identify patients at higher risk of rapid progression and poor outcome even when KLG and clinical risk factors are taken into account.

Evidence-based clinical guidelines: a new system to better determine true strength of recommendation.

RATIONALE, AIMS AND OBJECTIVES: Clinical practice guidelines often grade the 'strength' of their recommendations according to the robustness of the supporting research evidence. The existing methodology does not allow the strength of recommendation (SOR) to be upgraded for recommendations for which randomized controlled trials are impractical or unethical. The purpose of this study was to develop a new method of determining SOR, incorporating both research evidence and expert opinion. METHODS: A Delphi technique was employed to produce 10 recommendations for the role of exercise therapy in the management of osteoarthritis of the hip or knee. The SOR for each recommendation was determined by the traditional method, closely linked to the category of research evidence found on a systematic literature search, and on a visual analogue scale (VAS). Recommendations were grouped A-D according to the traditional SOR allocated and the mean VAS calculated. Difference across the groups was assessed by one-way ANOVA variance analysis. RESULTS: Mean VAS scores for the traditional SOR groups A-D and one proposition which was 'not recommended' showed significant linearity on one-way ANOVA. However, certain recommendations which, for practical reasons, could not assessed in randomized controlled trials and therefore could not be recommended strongly by the traditional methodology, were allocated a strong recommendation by VAS. CONCLUSIONS: This new system of grading strength of SOR is less constrained than the traditional methodology and offers the advantage of allowing SOR for procedures which cannot be assessed in RCTs for practical or ethical reasons to be upgraded according to expert opinion.

Predictors of hip joint replacement in new attenders in primary care with hip pain.

BACKGROUND: Studies investigating the factors associated with need for total hip replacement should ideally be based on prospective investigation of new attenders in primary care. AIM: To determine the incidence of listing for total hip replacement, and its predictors, among attenders in primary care with a new episode of hip pain. DESIGN OF STUDY: Prospective multicentre cohort study. SETTING: One hundred and ninety-five patients (mean age = 63 years, 68% female) with new episode of hip pain, attending primary care between November 1994 and October 1997. At the first visit, patients were evaluated for indices of pain and disability, range of hip movement, and radiographic changes of osteoarthritis. METHOD: General practitioner participants were recruited from the membership of the Primary Care Rheumatology Society to recruit all consecutive attenders with a new episode of hip pain. Annual follow-up was carried out to determine which patients were being 'put on a waiting list' for total hip replacement. RESULTS: Seven per cent of patients were put on a waiting list for total hip replacement within 12 months and 23% of patients within four years. At presentation, pain duration, pain severity, (including the need to use a stick) and restriction of internal rotation were the major clinical predictors of being put on a waiting list. Radiographic predictors of osteoarthritis performed similarly to the clinical measures. A simple scoring system based on both radiographic severity and two of the clinical measures was derived that identified groups at high likelihood of being put on a waiting list (sensitivity = 76%) with a low false-positive rate (specificity = 95%). CONCLUSION: New primary care attenders with pain are frequently accepted for total hip replacement soon after their first attendance--a decision that can be predicted by simple clinical measures.