What’s my chance of becoming “disabled”?

For me, one of the scariest aspects of rheumatoid arthritis is the prospect of being unable to keep my job, especially after the nine years of college and graduate school it took to earn it!  According to WebMD, approximately 1 of 3 RA sufferers end up leaving their careers.  This fear is what prompted me to read a recent article titled “Development of Functional Impairment and Disability in Rheumatoid Arthritis Patients Followed for 20 Years…” by Meliha Kapetanovic, et al.  that was recently published in the journal Arthritis Care and Research.

This studied followed 171 patients, in Sweden I believe, for 20 years.  Patients were diagnosed in 1985 – 1989.  The average age was 52 years, which is toward the higher end of the range reported by the Arthritis Foundation for the average age of diagnosis (30 – 60).  The majority of patients in the study were female (63%), which is a little lower than what is currently estimated (70 – 80% of rheumatoid arthritis patients are female according to the Arthritis Foundation).

Scarily, 40% of the study participants died during the study, but the research didn’t distinguish whether causes of death were due to RA or not.  The average age of death in Sweden is approximately 82 years. At the end of twenty years, the average age of study participants was 72 years, with a standard deviation of 12 years. Therefore, approximately 21% of patients are expected to be above 82 years old at the end of the study.  That leaves approximately 19% of the study participants whose deaths are not easily attributed to “averages”.  This is consistent with other studies that have showed a higher incidence of death, mostly due to cardiovascular causes, due to RA (Sihoven 2004).  I knew this from other articles I’ve read – but it’s still scary to see again!!!

The study tracked disease activity, functional impairment, disability, and radiologic damage over the 20 years.  Functional impairment, measured by the ability to move different joints, grip things, touch your toes, etc., was related to joint damage and increased steadily with time.  Over the twenty years, functional impairment doubled on average.  Disability was measured using self-reported difficulties in performing various activities.  It increased for 10 years and then leveled off.  Radiological damage progressed rapidly during the first 5 years and then gradually increased. Comorbidity (or diagnosis with additional diseases) increased over the entire 20 years.

One thing I questioned initially with these trends was whether the introduction of biologics played a role in diminishing the progression of joint damage with time.  However, a quick search found that most of the biologics weren’t broadly distributed until the mid 2000’s, or near the conclusion of the study.  In contrast, methotrexate was first approved for RA use in 1988.  Thus, the decline in joint damage progression after 5 years could be due to increasing use of methotrexate during the first 5 – 9 years of the study. This is just a observation – there’s not enough evidence in the article to support or disprove this conjecture.

Kapetanovic, et al. 2015.  Arthritis Care and Research. v 67, no 3, pp 340 -348.  Figure 2.

Kapetanovic, et al. 2015. Arthritis Care and Research. v 67, no 3, pp 340 -348. Figure 2.

So what does contribute to disability? The figure at left summarizes the factors contributing to impairment and disability. The percent on the left axis represents the percentage of variability in the outcome (disability or impairment) that associated with the independent variable (e.g., age, sex).  The study showed that disease activity was the largest contributor to disability (HAQ), while radiologic damage was the largest contributor to impairment (SOFI).  Comorbidity, age, and sex contributed to impairment and disability, but to a much lesser extent.  It’s really important to notice that only 50% (at most) of the variability in disability and impairment is accounted for.  The authors conjecture that the assessments of disease activity were incomplete.  They note that measures of pain, fatigue, and morning stiffness were not collected.  They also conjecture that “psycosocial impairment and coping strategies may have an impact.”  (No duh! In laymen’s term this means that the psycological and social impacts of having RA, and how we have to deal with it, may impact our perception of being able to function).

Overall, this article didn’t answer the question I initially posed, but I feel it does provide motivation to keep my disease activity as low as possible! On the days that the side effects of all the meds seem to outweigh the benefits, this study is one I’ll remember.  The good news from the study is that factors completely outside our control, like sex, age, and comorbidity, are NOT major contributors to disability.  While it seems like disease activity is completely out of my control most days, I intellectually know that by being assertive with my doctor and staying on top of my Remicade and methotrexate, I can help decrease my disease activity.  Plus, this study doesn’t capture the potential of biologics, which have helped many people control their RA and even go in remission.