Work Factors Are Still Better Indicators of Rheuma

Newswise — Work factors, such as working few hours and being self-employed, continue to be the most important predictors of work disability and loss among patients with rheumatoid arthritis, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Boston, Mass.

Rheumatoid arthritis is a chronic disease that causes pain, stiffness, swelling, and limitation in the motion and function of multiple joints. Though joints are the principal body parts affected by RA, inflammation can develop in other organs as well. An estimated 2.1 million Americans have RA, most of them women.

Work disability occurs in as much as 6 percent of patients with RA annually; Social Security Disability occurs in nearly two percent annually.

Drugs known as anti-TNF inhibitors are often prescribed to individuals with rheumatoid arthritis, and they work by targeting and blocking the inflammation, and can help reduce pain, morning stiffness, and tender or swollen joints. To determine the effect of anti-TNF therapy on work disability and premature work loss in patients with RA, researchers conducted two studies.

The first study evaluated 8,082 patients with RA, who were employed when diagnosed with RA. Researchers followed participants for up to five and a half years—as long as they remained under the age of 62.

At an average of 12.8 years after the onset of RA, 44 percent of the participants in this study were no longer employed, nearly twenty-three percent considered themselves disabled, and nearly twenty-one percent were receiving SSD.

Researchers determined that anti-TNF therapy was not positively or negatively associated with the risk of work disability. They did, however, find that other factors such as college education (making participants more likely to remain working) and smoking (making participants more likely to experience work disability) had an impact.

During the second study, researchers wanted to determine if anti-TNF therapy can prevent premature work loss after controlling for differences among participants in demographics, disease severity, and work factors.

Participants completed four surveys over three years in this study. All were employed and under the age of 64 at the time of the first survey. Forty-eight percent of the participants were using anti-TNF therapy.

In this study, 231 participants were not working from the time of the second survey on. They were compared with 722 participants who remained employed full time for the duration of the study. Factors associated with premature work cessation included working fewer hours, earning a lower income, and being self-employed " along with older age and more severe disease.

As with work disability measured in the first survey, researchers determined that anti-TNF therapy had little to do with work loss in these patients with RA.

"Work disability is a major cost of rheumatoid arthritis, and it is hoped this cost will be reduced by anti-TNF therapy. However, these studies found no evidence that anti-TNF therapy reduces rheumatoid arthritis work disability," said Saralynn Allaire, ScD; professor of medicine, Boston University School of Medicine; and an investigator in both studies. "It may take longer to see the effects of this therapy on work disability, since it works best when used in the very first stages of disease, or more powerful treatments may be needed."

The ACR is an organization of and for physicians, health professionals, and scientists that advances rheumatology through programs of education, research, advocacy and practice support that foster excellence in the care of people with or at risk for arthritis and rheumatic and musculoskeletal diseases. For more information on the ACR's annual meeting, see http://www.rheumatology.org/annual.

Editor's Notes:

Frederick Wolfe, MD, will be presenting "The Prevalence, Incidence, and Effect of Anti-Tumor Necrosis Factor (TNF) on Work Disability in Rheumatoid Arthritis" during the ACR Annual Scientific Meeting at the Boston Convention and Exhibition Center from 4:30pm " 6:00pm ET on Thursday, November 8, 2007, in Grand Ballroom East.

Dr. Allaire will be presenting "No Evidence of Reduction in Premature Work Loss among Persons with Rheumatoid Arthritis (RA) Using Anti-TNF Alpha Agents" during the ACR Annual Scientific Meeting at the Boston Convention and Exhibition Center from 4:30 " 6:00pm ET on Saturday, November 10, 2007, in Room 156. Dr. Allaire will be available for media questions and briefing at 1:30 am ET on Thursday, November 8 in the on-site press conference room, Room 251.

Presentation Number: 729

The Prevalence, Incidence, and Effect of Anti-Tumor Necrosis Factor (TNF) on Work Disability in Rheumatoid Arthritis

Frederick Wolfe1, Saralynn Allaire2, Kaleb Michaud3. 1National Data Bank for Rheumatic Diseases, Wichita, KS; 2Boston University, Boston, MA; 3University of Nebraska Medical Center, Omaha, NE

Purpose: Rheumatoid arthritis (RA) leads to work disability in many persons with the disorder. Work disability varies with severity of illness, but also with economic conditions and governmental social policies. Modern RA treatments that reduce disease activity, such as anti-tumor necrosis factor (TNF) therapy, might reduce the rate of work disability. In this study we determined the effect of anti-TNF therapy on work disability, as well as the prevalence and incidence of work disability in RA.

Methods: We used a longitudinal data bank to evaluate work disability in 8,082 RA patients who were employed when RA was diagnosed. Patients were followed for up to 5.5 years as long as they were less than 62 years of age. Reported work disability and Social Security disability (SSD) incidence rates were determined in a subset (N = 4,155) of those employed at study onset. The effect of anti-TNF therapy on work disability was determined by conditional logistic regression, after adjustment for covariates that included demographic factors, comorbidity, and clinical variables that included HAQ, symptom intensity scale, count of prior DMARDS, corticosteroid use, RADAI joint score, VAS pain, total joint arthroplasty, NSAID and analgesic use.

Results: At a median of 12.8 years after RA onset, 56.2% were still employed, 43.8% were not working, and 22.7% considered themselves disabled. In addition, 30.5% had stopped work over their lifetimes for health reasons and 20.6% were currently receiving SSD. The annualized incidence rate for self-reported work disability was 2.5% (95% CI 2.2%-2.8%) and for SSD was 1.9% (95% CI 1.7%-2.2%). The annualized incidence rate for persons who stopped working for any cause and did not resume employment was 4.0%. Almost all study variables were predictive of work disability. In multivariable analyses, college education had a strong protective effect, odds ratio (OR) 0.4, and smoking had strong negative effect, OR 1.9. Among clinical variables, treatment with corticosteroids and analgesics were predictive of work disability (OR 1.5), as was a 1 unit increase in HAQ score (OR 3.4), joint score (OR 1.04), and total joint arthroplasty (OR 2.9). Anti-TNF use was not associated with the risk of SSD, odds ratio 1.2 (95% CI 0.8 to 1.8), p = 0.441, but was associated with an increased risk of self-reported work disability, odds ratio 1.6 (95% CI 1.1 to 2.4, p=0.014, after adjustment for covariates.

Conclusions: Work disability occurs in 2.5% of RA patients annually, and SSD in 1.9%. Cross-sectional rates of self-reported disability are lower than noted in previous studies, perhaps reflecting overall improvement in RA therapy. We could not discern a protective effect of anti-TNF therapy on the risk of work disability. Possible reasons for this finding include insufficient efficacy of anti-TNF therapy, as well as the possibility that covariate control was incomplete.

Disclosure Block: F. Wolfe, Centocor, Abbott, Bristol-Myers Squibb, Amgen, 2; S. Allaire, None; K. Michaud, None.

Presentation Number: 2119

No Evidence of Reduction in Premature Work Loss among Persons with Rheumatoid Arthritis (RA) Using Anti-TNF Alpha Agents

Saralynn Allaire1, Frederick Wolfe2, Jingbo Niu1, Michael LaValley3. 1Boston University School of Medicine, Boston, MA; 2National Data Bank for Rheumatic Diseases, Wichita, KS; 3Boston University School of Public Health, Boston, MA

Purpose: Due to their high cost there is interest in determining whether anti-TNF? agents reduce work disability, a major cost of RA. In a prior study, subjects using an anti-TNF? agent were more likely to work than those who did not, but the difference was not quite significant, and samples from 2 different studies were compared. Our objective was to ascertain the importance of anti-TNF? use vs. demographic, disease, work and work preference characteristics as a risk factor for premature work cessation in a single US cohort of RA patients.

Methods: Within this RA cohort we conducted a nested case-control study. Subjects completed consecutive biannual surveys over 2 years between 2002-5 and were employed and aged < 64 in the first survey. 231 cases were not working in the 2nd through 4th surveys. 722 controls matched 3:1 to cases by time of 1st survey were employed in all surveys. Anti-TNF? agents were infliximab, etanercept and adalimumab. Disease factors were severity (functional limitation assessed by HAQ and RA global severity by 0-10 scale) and duration. Subjects reported on medications taken in the past 6 months and on work and work preference characteristics examined in other studies. We used conditional logistic regression to determine the relative importance of baseline factors to case status. Due to collinearity, disease severity was limited to global severity in the final model; inclusion of this factor reduced possible confounding by indication related to anti-TNF? use. To assess the importance of factors, reductions in likelihood ratio chi-square statistics were examined when demographic, disease, anti-TNF? use, work and work preference factors were removed from the regression models.

Results: 953 subjects' mean age was 52, 82% female, 93% White, and 70% > high school education. Mean disease duration was 14 years; mean HAQ score was 0.9; 48% used an anti-TNF? agent. 66% worked full time; 42% preferred to work full time, while 42% preferred part time and 16% not to work. 43% had professional or managerial jobs, and 20% had stressful jobs (high demand, low control). Anti-TNF? use did not predict work cessation in either bivariate or multivariate analyses (Table) and produced no reduction in the likelihood ratio when removed. As in a 1995 study, preferring not to work produced the largest likelihood ratio reduction, followed by work factors.

Conclusions: Use of anti-TNF? agents did not reduce premature work cessation in this sample with long term disease on average. Work related factors were the most important predictors, as in previous studies.

Effect of Risk Factors on Premature Work CessationRisk Factor Odds ratio (CL)Increasing age (2 years) 1.08 (1.02-1.13)**Male gender 1.12 (0.65-1.94)High school education or less 1.24 (0.80-1.90)Personal income US median or less 1.75- (1.08-2.85)*Greater RA global severity (1 unit) 1.12 (1.03-1.22)*Increasing disease duration (2 years) 1.02 (0.98-1.06)Use anti-TNF agent 1.13 (0.77-1.64)Fewer hours worked per week (5 hours) 1.11 (1.03-1.20)**Greater commuting difficulty 1.04 (0.99-1.08)Self-employed vs. not 1.84 (1.15-2.93)*Professional/managerial job 0.78 (0.50-1.22)Stressful job 1.59 (0.99-2.55)Prefer to work part time vs. not to work 0.37 (0.23-0.60)**Prefer to work full time vs. not to work 0.23 (0.14-0.39)***p<.05; **p<.01

Disclosure Block: S. Allaire, None; F. Wolfe, Abbott, Amgen, Bristol-Myers-Squibb, Centocor, 2; J. Niu, None; M. LaValley, None.