Objective. To quantify the incidence of symptomatic hand, hip, and knee osteoarthritis (OA) among members of the Fallon Community Health Plan, a health maintenance organization located in central Mas- sachusetts.Methods. Incident OA was defined as the first evidence of OA by radiography (grade 2 2 on the Kellgren-Lawrence scale of [0][1][2][3][4] plus joint symptoms at the time the radiograph was obtained or up to 1 year before the radiograph was obtained.Results. and women had higher rates than men, especially after age 50. A leveling off or decline occurred for both groups around the age of 80.Conclusion. In a large study of symptomatic OA we observed incidence rates that increased with age. In women ages 70-89, the incidence of knee OA approached 1% per year.Most people over the age of 65 have some radiographic evidence of osteoarthritis (OA), which is the most common joint disorder (1-3). The prevalence of OA increases with age and is higher in women than in men, especially among the elderly (1-12). OA has a major impact on disability in the elderly as well as on the cost of care in that population (1,(13)(14)(15).Studies describing the frequency of OA have, almost without exception, been prevalence surveys (1,3). These are useful for quantifying the disease burden in a population, but may give an erroneous picture of the incidence, if there are different mortality rates in diseased and nondiseased groups. Monson and Hall (16) and Cerhan et a1 (17) have suggested that individuals with OA have higher rates of mortality than do those without OA, making incidence studies a crucial part of the epidemiologic description of OA. Prevalence surveys (2,4,7,10,18,19) have focused on the prevalence of radiographic disease, in large part because it is more common and easier to define than symptomatic OA. Many patients with radiographic evidence of OA do not have symptoms, but it is symptomatic OA that causes pain, suffering, disability, and utilization of health care resources.The purpose of the present study was to quantify the incidence of clinically symptomatic OA of the hand, hip, and knee. We identified incident cases among members of a health maintenance organization (HMO), the Fallon Community Health Plan (FCHP).

Because of a "healthy responder effect," secular trends in mortality based on cohort studies may be biased if based on responders only. Because responders are selected on the basis of their health at study entry, subjects just entering a study are not comparable with subjects who have been in the study for several years. The result may be an artificial increase in mortality, which impedes analyzing the effect of secular trends in risk factors on mortality. The objective of this paper is to suggest a solution by using data on nonresponders and applying a sensitivity analysis. We illustrate this solution with data on trends in smoking prevalence and all-cause mortality based on a large Danish cohort study with 19 years of complete follow-up on responders and nonresponders. Secular trends in mortality based on the whole sample vs responders only illustrated that results based on responders were biased. In a sensitivity analysis, the observed person-years of nonresponders were distributed among six categories of persons with respect to smoking behavior (never-smokers; ex-smokers; noninhaling current smokers; and current smokers of 1-14, 15-24, and > or =25 gm tobacco per day) according to preset assumptions regarding smoking habits. The observed deaths among nonresponders were then distributed on the six smoking categories according to relative risks derived from a Poisson regression analysis among responders. This procedure allowed us to study the effect of adjustment for smoking on the unbiased secular trend in mortality. By applying different assumptions regarding smoking habits among nonresponders, we explored the effect of the assumptions on the adjusted secular trend in mortality. We conclude that secular trends in mortality based on responders in a cohort study are likely to be biased. If complete follow-up on nonresponders is available, this method could prove useful in other cohort studies.

Studies have shown a positive association between obesity and knee osteoarthritis. Studies evaluating hand or hip osteoarthritis and weight, however, have assessed x-ray osteoarthritis or been cross-sectional, or both, and results of these have been inconsistent. We assessed the association between body weight, body mass index, and incident symptomatic osteoarthritis in 134 matched case-control pairs of women who were part of a case-control study on estrogen replacement therapy and osteoarthritis. We identified incident symptomatic osteoarthritis cases of the hand, hip, and knee in women ages 20-89 years who were members of a health plan between January 1, 1990 and December 31, 1993. For each case we selected a control woman who was matched by closest date of birth to the case. Medical records were reviewed to obtain weight and height information for the period before disease onset. After controlling for estrogen use, smoking status, height, and health care use, we found that body weight was a predictor of incident osteoarthritis of the hand, hip, and knee. Odds ratios ranged from 3.0 to 10.5 for women in the upper tertiles of weight compared with women in the lowest tertile. Similar associations were observed for body mass index. Our results suggest that obesity is associated with the development of incident osteoarthritis at all joints studied.

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