Robert F. Meenan

Effect sizes for interpreting changes in health status

Health status measures are being used with increasing frequency in clinical research. Up to now the emphasis has been on the reliability and validity of these measures. Less attention has been given to the sensitivity of these measures for detecting clinical change. As health status measures are applied more frequently in the clinical setting, we need a useful way to estimate and communicate whether particular changes in health status are clinically relevant. This report considers effect sizes as a useful way to interpret changes in health status. Effect sizes are defined as the mean change found in a variable divided by the standard deviation of that variable. Effect sizes are used to translate “the before and after changes” in a “one group” situation into a standard unit of measurement that will provide a clearer understanding of health status results. The utility of effect sizes is demonstrated from four different perspectives using three health status data sets derived from arthritis populations administered the Arthritis Impact Measurement Scales (AIMS). The first perspective shows how general and instrument-specific benchmarks can be developed and how they can be used to translate the meaning of clinical change. The second perspective shows how effect sizes can be used to compare traditional clinical measures with health status measures in a standard clinical drug trial. The third application demonstrates the use of effect sizes when comparing two drugs tested in separate drug trials and shows how they can facilitate this type of comparison. Finally, our health status results show how effect sizes can supplement standard statistical testing to give a more complete and clinically relevant picture of health status change. We conclude that effect sizes are an important tool that will facilitate the use and interpretation of health status measures in clinical research in arthritis and other chronic diseases.

Obesity and Knee Osteoarthritis: The Framingham Study

STUDY OBJECTIVE To determine whether obesity preceded knee osteoarthritis and was thus a possible cause. DESIGN Cohort study with weight and other important variables measured in 1948 to 1951 (mean age of subjects, 37 years) and knee arthritis evaluated in 1983 to 1985 (mean age of subjects, 73 years). SETTING Population-based participants; a subset (n = 1420) of the Framingham Heart Study cohort. METHODS For those subjects in the Framingham Study having knee radiographs taken as part of the 18th biennial examination (1983 to 1985), we examined Metropolitan Relative Weight, a measure of weight adjusted for height at the onset of the study (1948 to 1951). Relative risks were computed as the cumulative incidence rate of radiographic knee osteoarthritis in the heaviest weight groups at examination 1 divided by the cumulative rate in the lightest 60% weight groups at examination 1. Relative risks were adjusted for age, physical activity level, and uric acid level. RESULTS In 1983 to 1985, 468 subjects (33%) had radiographic knee osteoarthritis. For men, the risk of knee osteoarthritis was increased in those in the heaviest quintile of weight at examination 1 compared with those in the lightest three quintiles (age-adjusted relative risk, 1.51; 95% confidence interval [CI], 1.14 to 1.98); risk was not increased for those in the second heaviest quintile (relative risk, 1.0). The association between weight and knee osteoarthritis was stronger in women than in men; for women in the most overweight quintile at examination 1, relative risk was 2.07 (95% CI, 1.67 to 2.55), and for those in the second heaviest group, relative risk was 1.44 (95% CI, 1.11 to 1.86). This link between obesity and subsequent osteoarthritis persisted after controlling for serum uric acid level and physical activity level, and was strongest for persons with severest radiographic disease. Obesity at examination 1 was associated with the risk of developing both symptomatic and asymptomatic osteoarthritis. CONCLUSIONS These results and other corroborative cross-sectional data show that obesity or as yet unknown factors associated with obesity cause knee osteoarthritis.

Work Disability in Rheumatoid Arthritis: Effects of Disease, Social, and Work Factors

We explore here the relative contribution of selected disease, social, and work-related factors to disability status in a population of persons with rheumatoid arthritis. Our study differs from previous studies in that it is limited to one diagnostic entity, yet at the same time evaluates a broad range of social and work-related factors in disability. One hundred-eighty persons with rheumatoid arthritis sampled from 19 socially diverse practice settings were given a structured survey about their medical and work histories and social backgrounds. We found significant effects of stage and duration of illness on continued employment but no positive effect of selected therapies. Social and work factors combined had a far larger effect on work disability than all disease factors. Among work factors, control over the pace and activities of work and self-employment status had the greatest effect on continued employment, suggesting that time control issues are crucial to the maintenance of ones job after onset of this illness.

Health status assessment for elderly patients. Report of the Society of General Internal Medicine Task Force on Health Assessment.

A brief but systematic assessment of functional status should be incorporated into the routine medical management of elderly patients, because of its demonstrated usefulness.

HEALTH STATUS REPORTS IN THE CARE OF PATIENTS WITH RHEUMATOID ARTHRITIS

We examined the use of formal health status reports every 3 months over 1 year in the clinical care of patients with rheumatoid arthritis (RA). The reports consisted of single-page, computer-generated summaries of scores derived from either the AIMS (Arthritis Impact Measurement Scales) or the MHAQ (Modified Health Assessment Questionnaire) health status questionnaires. A total of 1920 subjects from 27 community practice sites were randomly assigned to three study groups in each practice: intervention, attention placebo and control. Results showed that 55% of the physicians found the reports to be at least moderately useful as an aid to patient management, primarily for improving the doctor-patient relationship. However, no detectable differences among the three groups were seen in terms of medication compliance, number of physician visits, number of referrals, frequency of major medication changes, attitudes towards the physician, patient satisfaction or change in health status over 1 year. The failure to demonstrate objective benefits of health status reports in this study may be due to physician unfamiliarity with health status scores, failure to link the report with an office visit, the relative stability of clinical status in the subjects over 1 year and the relatively short time-frame of the study.

The costs of rheumatoid arthritis.

SummaryThe economic costs associated with rheumatoid arthritis (RA). a chronic. systemic. inflammatory disorder that affects many joints. are high. approximating those of coronary heart disease. The estimated prevalence of RA in the US is 0.9%. Incidence increases with age. and is highest among women in the fourth to sixth decades of life, The primary impact of RA is due to the significant morbidity associated with this disease. Mortality is increased among a poorly defined subgroup of RA patients. The average level of disability among RA patients is moderate. but 6.5 to 12% of patients are severely disabled. Between one- and two-thirds of prev iously employed patients have a reduced work capacity.Treatment primarily involves the use of nonsteroidal anti -inflammatory drugs and disease modifying <lntirheumatic drugs. Rehabilitation measures and orthopaedic surgery are also used. Total annual direct costs of RA (total charges) have been calculated to be

Reducing work disability associated with rheumatoid arthritis: Identification of additional risk factors and persons likely to benefit from intervention

US5275 and

Evidence for decline in disability and improved health among persons aged 55 to 70 years: the Framingham Heart Study.

US6099 ( 1991 dollars) per patient. Lifetime medical care charges were estimated at SUS 12578 per patient (1991 dollars).The dircct costs of RA are substantial, but indirect costS have been calculated to be much higher because of extensive morbidity. The difference between the direct and indirect costs of RA is decreasing because salary increases have nOi kept pace with risin g heahhcare costs. The latter arc increasing rapidly in RA because of the use of new technology. surgical procedures. and the greater use of drugs with frequent monitoring requirements and significant toxicity. Because intangible costs such as pain form a substantial part of the overall costs ofRA but are difficult to evaluate. cost estimates inevitably underestimate the impact of the disease on individuals and society.

The stability of health status in rheumatoid arthritis: a five-year study of patients with established disease.

OBJECTIVE To study additional risk factors for rheumatoid arthritis (RA)-related work disability and to identify the groups of individuals at high risk and the potentially modifiable factors which place them at risk. METHODS A cross-sectional mail survey was conducted among 469 adults with RA. Work disability was defined as unemployment due to RA. A broad range of explanatory factors was examined, including sociodemographic, health, work, support given by others, and commuting difficulty. Employed and work-disabled subjects were compared by t-test and chi-square. Attributable fractions were calculated to assess the predictive value of factors. A recursive partitioning procedure identified individuals at varying risks for work disability, and their characteristics were defined. RESULTS The risk factors joint pain and functional status, commuting difficulty, physical demands of the job, and disease duration were important predictors of work disability in both the attributable fraction and recursive partitioning analytic models. Having a professional or administrative job was protective, provided the salary earned was not low. Younger individuals with RA of shorter duration were placed at high risk by potentially modifiable factors. While older persons with RA of long duration were at high risk, modifiable factors could not be identified. CONCLUSION Commuting difficulty, a previously overlooked factor, is an important predictor of RA work disability. Younger individuals with RA of relatively short duration can be placed at high risk by potentially modifiable factors including commuting difficulty, physically demanding jobs, greater joint pain and poor functional status, and nonprofessional/non-administrative jobs.

Misuse of statistical methods in Arthritis and Rheumatism. 1982 versus 1967-68.

OBJECTIVES This study detected secular change in disability and health among persons aged 55 to 70 years, the life period when increases in disability and morbidity begin and retirement occurs. METHODS Cross-sectional comparisons were completed with data from similarly aged members of the original (n = 1760) and offspring (n = 1688) cohorts of the Framingham Heart Study, which represent 2 generations. Analyses were conducted by gender and on chronic disease subgroups by logistic regression. RESULTS There was substantially less disability in the offspring cohort than in the original cohort. Thirty-six percent of offspring men were disabled vs 52% of original cohort men (P = .001); among women, these proportions were 54% vs 72% (P = .001). Fewer offspring perceived their health as fair or poor and fewer had chronic diseases. Offspring were more physically active and less likely to smoke or consume high amounts of alcohol, but their average weight was greater. The secular decline in disability was strongly evident among individuals with chronic diseases. CONCLUSIONS Our findings depict a secular change toward a less disabled and globally healthier population in the period of life when retirement occurs.