Rachel Duncan

Clinical classification criteria for knee osteoarthritis: performance in the general population and primary care

Background: Doubts have been expressed about the performance of the American College of Rheumatology (ACR) clinical classification criteria for osteoarthritis when applied in the general population. Objective: To investigate whether the distribution of population subgroups and underlying disease severity might explain the performance of these criteria in the population setting. Methods: Population-based cross-sectional study. 819 adults aged ⩾50 years reporting knee pain in the last 12 months were clinically assessed by research therapists using standardised protocols and blinded to radiographic status. All participants underwent plain radiography of the knees, scored by a single reader blinded to clinical status. The relationship between fulfilling the ACR clinical classification criteria for knee osteoarthritis and the presence of symptomatic radiographic knee osteoarthritis was summarised for the sample as a whole and within subgroups. Results: Radiographic osteoarthritis was present in 539 participants (68%) and symptomatic radiographic knee osteoarthritis in 259 (33%). 238 participants (30%) fulfilled the ACR clinical criteria for knee osteoarthritis. Agreement between the ACR clinical criteria and symptomatic radiographic knee osteoarthritis was low (sensitivity 41%; specificity 75%; positive predictive value 44%; negative predictive value 72%). Sensitivity and specificity did not vary markedly between population subgroups, although they were influenced by the underlying severity of radiographic osteoarthritis. Conclusion: The ACR clinical criteria seem to reflect later signs in advanced disease. Other approaches may be needed to identify early, mild osteoarthritis in the general population and primary care.

The Knee Clinical Assessment Study – CAS(K). A prospective study of knee pain and knee osteoarthritis in the general population

BackgroundKnee pain affects an estimated 25% of the adult population aged 50 years and over. Osteoarthritis is the most common diagnosis made in older adults consulting with knee pain in primary care. However, the relationship between this diagnosis and both the current disease-based definition of osteoarthritis and the regional pain syndrome of knee pain and disability is unclear. Expert consensus, based on current evidence, views the disease and the syndrome as distinct entities but the clinical usefulness of these two approaches to classifying knee pain in older adults has not been established. We plan to conduct a prospective, population-based, observational cohort study to investigate the relative merits of disease-based and regional pain syndrome-based approaches to classification and prognosis of knee pain in older adults.MethodsAll patients aged 50 years and over registered with three general practices in North Staffordshire will be invited to take part in a two-stage postal survey. Respondents to this survey phase who indicate that they have experienced knee pain within the previous 12 months will be invited to attend a research clinic for a detailed assessment. This will consist of clinical interview, physical examination, digital photography, plain x-rays, anthropometric measurement and a brief self-complete questionnaire. All consenting clinic attenders will be followed up by (i) general practice medical record review, (ii) repeat postal questionnaire at 18-months.

Does isolated patellofemoral osteoarthritis matter

OBJECTIVES To describe the structure-pain and structure-function associations in isolated patellofemoral osteoarthritis (PF OA). DESIGN Population-based study of 819 adults aged > or =50 years with knee pain. The severity of knee pain, stiffness and disability were measured using the Western Ontario and McMaster Osteoarthritis Index (WOMAC). Three radiographic views of the knee were obtained. RESULTS Isolated PF OA was mild in 142 participants and moderate/severe in 44. Mean WOMAC scores for pain, stiffness and function were associated with radiographic severity of PF OA (F(2,389)=4.7, P=0.01; F(2,392)=4.5, P=0.012 and F(2,392)=6.1, P=0.002, respectively, adjusted for age, gender, and body mass index (BMI)). Post-hoc tests demonstrated statistically significant differences for mean pain, stiffness and function score between those with mild PF OA and those with normal X-rays. In task-specific items there was evidence of a stepped response, the proportion of participants with moderate/severe/extreme pain or difficulty in performing everyday tasks increasing with the severity of PF OA. The strongest association was observed for pain going up and down stairs (age-gender-BMI adjusted odds ratio (OR) 3.0; 95% confidence interval (CI) 1.4,6.6. Functional tasks most strongly related to radiographic severity were: descending stairs (OR 3.2; (CI 1.5,6.5)), getting in/out of the bath (3.2; 1.5,6.6), getting in/out of a car (3.0; 1.4,6.1). CONCLUSIONS Mild isolated PF OA is significantly associated with symptoms of pain, stiffness and functional limitation. Further research on its recognition in clinical practice and the development of targeted treatments to prevent or slow progression are warranted.

How do pain and function vary with compartmental distribution and severity of radiographic knee osteoarthritis

OBJECTIVES In radiographic OA (ROA) of the knee, how does radiographic severity and pattern of compartmental involvement influence symptoms? METHODS Population-based study of 819 adults aged > or =50 yrs with knee pain. The severity of knee pain and function were measured using the Western Ontario and McMaster Universities scale. Three radiographic views of the knees were obtained. RESULTS Seven hundred and seventy-seven participants were eligible (mean age 65.5 yrs, 357 males). Higher ROA severity in each of the tibiofemoral (TF) and patellofemoral (PF) compartments was independently associated with higher mean pain scores (TF: F(2, 700) = 9.0, P < 0.0001, PF: F(2, 700) = 12.7, P < 0.0001). The same pattern was found for mean function scores (TF: F(2, 705) = 7.1, P = 0.001, PF: F(2, 705) = 15.9, P < 0.0001). If either the TF or PF compartment was affected by moderate/severe OA, the added presence of OA in the other compartment did not increase the mean pain or function scores. CONCLUSIONS It is the severity of radiographic disease within a compartment, rather than the distribution of radiographic disease between compartments that is associated with symptoms. ROA in the PF joint is associated with symptoms, emphasizing the importance of radiographic changes in his joint.

The Knee Clinical Assessment Study – CAS(K). A prospective study of knee pain and knee osteoarthritis in the general population: baseline recruitment and retention at 18 months

BackgroundSelective non-participation at baseline (due to non-response and non-consent) and loss to follow-up are important concerns for longitudinal observational research. We investigated these matters in the context of baseline recruitment and retention at 18 months of participants for a prospective observational cohort study of knee pain and knee osteoarthritis in the general population.MethodsParticipants were recruited to the Knee Clinical Assessment Study – CAS(K) – by a multi-stage process involving response to two postal questionnaires, consent to further contact and medical record review (optional), and attendance at a research clinic. Follow-up at 18-months was by postal questionnaire. The characteristics of responders/consenters were described for each stage in the recruitment process to identify patterns of selective non-participation and loss to follow-up. The external validity of findings from the clinic attenders was tested by comparing the distribution of WOMAC scores and the association between physical function and obesity with the same parameters measured directly in the target population as whole.Results3106 adults aged 50 years and over reporting knee pain in the previous 12 months were identified from the first baseline questionnaire. Of these, 819 consented to further contact, responded to the second questionnaire, and attended the research clinics. 776 were successfully followed up at 18 months. There was evidence of selective non-participation during recruitment (aged 80 years and over, lower socioeconomic group, currently in employment, experiencing anxiety or depression, brief episode of knee pain within the previous year). This did not cause significant bias in either the distribution of WOMAC scores or the association between physical function and obesity.ConclusionDespite recruiting a minority of the target population to the research clinics and some evidence of selective non-participation, this appears not to have resulted in significant bias of cross-sectional estimates. The main effect of non-participation in the current cohort is likely to be a loss of precision in stratum-specific estimates e.g. in those aged 80 years and over. The subgroup of individuals who attended the research clinics and who make up the CAS(K) cohort can be used to accurately estimate parameters in the reference population as a whole. The potential for selection bias, however, remains an important consideration in each subsequent analysis.

Incidence, progression and sequence of development of radiographic knee osteoarthritis in a symptomatic population

Objectives Symptomatic knee osteoarthritis (OA) is a common disabling condition. Attention has tended to focus on the tibiofemoral joint (TFJ). However, there is evidence that the patellofemoral joint (PFJ) is involved in many cases, but its place in the sequence of development and progression of knee OA is unclear. This study estimates the cumulative incidence, progression and inter-relationship of radiographic changes of OA in the TFJ and the PFJ in symptomatic adults. Methods A population-based observational cohort of 414 adults aged ≥50 years with knee pain who had knee x-rays (weight-bearing posteroanterior semiflexed, skyline and lateral views) in 2002–3 and again in 2005–6 (mean interval 36.7 months) was studied. The outcome measure was the development of incident or progressive radiographic OA. Results The 3-year cumulative incidences of patellofemoral joint osteoarthritis (PFJOA) and tibiofemoral joint osteoarthritis (TFJOA) were 28.8% and 21.7%, respectively. Corresponding estimates of 3-year cumulative progression were 18.9% and 25.3%. PFJOA at baseline was common and increased the risk of incident TFJOA (adjusted OR 2.2, 95% CI 1.1 to 4.1) but less clearly progression of TFJOA (adjusted OR 1.7, 95% CI 0.3 to 9.0). TFJOA at baseline increased the risk of PFJOA incidence and progression (adjusted OR 3.1, 95% CI 1.2 to 8.4 and OR 4.5, 95% CI 1.8 to 11.2, respectively). Conclusions These results suggest a common sequence in the development of radiographic knee OA in symptomatic adults beginning in the PFJ, with subsequent addition and progression of TFJOA. It is proposed that isolated symptomatic PFJOA may be one marker for the future development of TFJOA and a target for the early management of knee OA.

Predicting the course of functional limitation among older adults with knee pain: do local signs, symptoms and radiographs add anything to general indicators?

Objective: To determine the additional prognostic value of clinical history, physical examination and x-ray findings to a previously derived simple generic model (age, body mass index, anxiety and pain severity) in a cohort of older adults with knee pain. Methods: Prospective cohort study in community-dwelling adults in North Staffordshire. 621 participants (aged ⩾50 years) reporting knee pain who attended a research clinic at recruitment and were followed up by postal questionnaire at 18 months. Poor functional outcome was measured by the Physical Functioning Scale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 18-month follow-up defined in 60% of participants. Results: Three clinical history variables (bilateral knee pain, duration of morning stiffness and inactivity gelling) were independently associated with poor outcome. The addition of the “clinical history” model to the “generic” model led to a statistical improvement in model fit (likelihood ratio (LR)  = 24.84, p = 0.001). Two physical examination variables (knee tender point count and single-leg balance) were independently associated with poor outcome but did not lead to a significant improvement when added to the “clinical history and generic” model (LR = 6.34, p = 0.50). Functional outcome was significantly associated with severity of knee radiographic osteoarthritis (OA), but did not lead to any improvement in fit when added to the “generic, clinical history and physical examination” model (LR = 1.86, p = 0.39). Conclusions: Clinical history, physical examination and severity of radiographic knee OA are of limited value over generic factors when trying to predict which older adults with knee pain will experience progressive or persistent functional difficulties.

Gender difference in symptomatic radiographic knee osteoarthritis in the Knee Clinical Assessment – CAS(K): A prospective study in the general population

BackgroundA recent study of adults aged ≥50 years reporting knee pain found an excess of radiographic knee osteoarthritis (knee ROA) in symptomatic males compared to females. This was independent of age, BMI and other clinical signs and symptoms. Since this finding contradicts many previous studies, our objective was to explore four possible explanations for this gender difference: X-ray views, selection, occupation and non-articular conditions.MethodsA community-based prospective study. 819 adults aged ≥50 years reporting knee pain in the previous 12 months were recruited by postal questionnaires to a research clinic involving plain radiography (weight-bearing posteroanterior semiflexed, supine skyline and lateral views), clinical interview and physical examination. Any knee ROA, ROA severity, tibiofemoral joint osteoarthritis (TJOA) and patellofemoral joint osteoarthritis (PJOA) were defined using all three radiographic views. Occupational class was derived from current or last job title. Proportions of each gender with symptomatic knee ROA were expressed as percentages, stratified by age; differences between genders were expressed as percentage differences with 95% confidence intervals.Results745 symptomatic participants were eligible and had complete X-ray data. Males had a higher occurrence (77%) of any knee ROA than females (61%). In 50–64 year olds, the excess in men was mild knee OA (particularly PJOA); in ≥65 year olds, the excess was both mild and moderate/severe knee OA (particularly combined TJOA/PJOA). This male excess persisted when using the posteroanterior view only (64% vs. 52%). The lowest level of participation in the clinic was symptomatic females aged 65+. Within each occupational class there were more males with symptomatic knee ROA than females. In those aged 50–64 years, non-articular conditions were equally common in both genders although, in those aged 65+, they occurred more frequently in symptomatic females (41%) than males (31%).ConclusionThe excess of knee ROA among symptomatic males in this study seems unlikely to be attributable to the use of comprehensive X-ray views. Although prior occupational exposures and the presence of non-articular conditions cannot be fully excluded, selective non-participation bias seems the most likely explanation. This has implications for future study design.

The contribution of selected non-articular conditions to knee pain severity and associated disability in older adults

OBJECTIVE To estimate the contribution of selected non-articular conditions (NACs) to pain severity and functional limitation in community-dwelling older adults with knee pain. DESIGN Population-based, cross-sectional study of 745 adults aged 50 years and over with knee pain. Self-complete questionnaires, clinical history and physical examination were used to identify the presence of selected NACs that could cause pain around the knee. Regression analyses were used to compare levels of knee pain severity (0-20) and functional limitation (0-68) (Western Ontario and McMaster Universities osteoarthritis index physical function subscale [WOMAC-PF]), between those with one or more NACs and those with none (NACs-absent). RESULTS Two hundred and seventy-three (36.6%) participants had at least one NAC: widespread pain, n=159; low back pain with index leg referral, n=102; full-leg pain, n=88; hip arthritis, n=65; prepatellar, infrapatellar or pes anserine bursitis, n=35. The NACs group had significantly higher levels of pain severity and functional limitation than the NACs-absent group: 8.2(+/-4.6) vs 5.4(+/-3.8) and 27.9(+/-15.8) vs 16.8(+/-13.2), respectively. The groups did not differ with respect to severity of radiographic osteoarthritis (ROA). Having one or more NACs accounted for a significant proportion of the variance in WOMAC scores, above that which could be explained by age, gender, body mass index and severity of ROA. CONCLUSION NACs appear to be common in older adults with knee pain. They make a significant contribution to knee pain severity and functional limitation and are likely to represent additional, rather than alternative, causes of knee pain/functional limitation to osteoarthritis (OA). These factors should be taken into account in epidemiological studies of knee pain and OA.

The Clinical Assessment Study of the Hand (CAS-HA): a prospective study of musculoskeletal hand problems in the general population

BackgroundPain in the hand affects an estimated 12–21% of the population, and at older ages the hand is one of the most common sites of pain and osteoarthritis. The association between symptomatic hand osteoarthritis and disability in everyday life has not been studied in detail, although there is evidence that older people with hand problems suffer significant pain and disability. Despite the high prevalence of hand problems and the limitations they cause in older adults, little attention has been paid to the hand by health planners and policy makers. We plan to conduct a prospective, population-based, observational cohort study designed in parallel with our previously reported cohort study of knee pain, to describe the course of musculoskeletal hand problems in older adults and investigate the relative merits of different approaches to classification and defining prognosis.Methods/DesignAll adults aged 50 years and over registered with two general practices in North Staffordshire will be invited to take part in a two-stage postal survey. Respondents to the survey who indicate that they have experienced hand pain or problems within the previous 12 months will be invited to attend a research clinic for a detailed assessment. This will consist of clinical interview, hand assessment, screening test of lower limb function, digital photography, plain x-rays, anthropometric measurement and brief self-complete questionnaire. All consenting clinic attenders will be followed up by (i) general practice medical record review, (ii) repeat postal questionnaire at 18-months, and (iii) repeat postal questionnaire at 3 years.DiscussionThis paper describes the protocol for the Clinical Assessment Study of the Hand (CAS-HA), a prospective, population-based, observational cohort study of community-dwelling older adults with hand pain and hand problems based in North Staffordshire.