Arthritis and mortality in the epidemiological follow-up to the National Health and Nutrition Examination Survey I.

Subsets were analyzed of respondents from the Epidemiological Follow-up to the National Health and Nutrition Examination Survey I (NHANES I) who (1) answered a general arthritis question reflecting whether a doctor told the respondent that she or he had arthritis, (2) answered seven pain, swelling, and stiffness questions, and (3) had radiographs of knees and hips assessed for osteoarthritis at the time of the initial survey during the early 1970s. Data for the follow-up were collected between 1982 and 1984 and included 1,491 fatalities in the largest subsample analyzed here. The dependent variable was months of survival after the initial interview. No distinction was drawn between rheumatoid arthritis versus osteoarthritis. The NHANES I contained only limited information on rheumatoid arthritis versus osteoarthritis. Additional covariates included age, age squared, education, race, marital status, diastolic blood pressure, and body mass. After adjusting for age, no statistically significant associations emerged between answers to the general arthritis questions or any of the seven pain questions on the one hand, and mortality on the other. Similar statistically insignificant results were found when the association between radiographic diagnoses of osteoarthritis in the hips and months of survival was considered after adjusting for age. These statistically insignificant results persisted in repeated testing, which alternately included and excluded a number of covariates, and in separate subsamples of women, men, and persons older and younger than age 50. Some evidence was found, however, for a negative, statistically significant association between radiographic knee diagnoses of osteoarthritis and survival, especially among women, even after adjusting for covariates. These mixed results (1) do not discredit findings elsewhere suggesting that rheumatoid arthritis is associated with early death, since it is likely that the great majority of respondents answering in the affirmative to the general arthritis or seven pain questions in the NHANES I had osteoarthritis, and (2) suggest that future surveys should make greater attempts to distinguish between rheumatoid arthritis and osteoarthritis.