Análise da capacidade funcional de uma coorte brasileira de pacientes com artrite reumatoide.

Abstract

Rheumatoid arthritis is an inflammatory chronic disease with estimated global prevalence of 0.5 1%, characterized by morning stiffness, joint pain and swelling. If not controlled, the disease leads to progressive joint destruction, decreasing quality of life and functional capacity. To maintain this capacity involves being able to perform basic daily life activities, such as those related with personal hygiene, to carry objects, to get dressed, to eat and to deambulate. Limitations or to be unable to perform these activities implies in at least some functional disability usually measured, in rheumatoid arthritis patients, by one of the Health Assessment Questionnaire components. This dissertation s general aim was to analyze functional capacity variation, measured by the Health Assessment Questionnaire Disability Index, in a Brazilian cohort of rheumatoid arthritis patients followed at outpatients clinics for a year and to create a predictive model as result of several demographic and clinical features. The specific aims were: (i) to evaluate which of the variables that were previously reported in the literature have impact on the functional capacity of RA patients in a Brazilian cohort; (ii) to build a predictive model adjusted to the Brazilian reality with variables of feasible acquisition; and (iii) to evaluate if there is effect modification due to the interaction between disease activity and length of time in the study. We evaluated 1111 rheumatoid arthritis patients followed at 11 reference treatment centers for rheumatic diseases, all pertaining to the Unified Health System SUS, with prospective data collection. We applied linear mixed effects models to evaluate the variation in functional capacity, measured by Health Assessment Questionnaire Disability Index, within the data collected at three time points along one year. This analysis revealed that, in the evaluated population, sex, socioeconomic status, joint pain, previous use of immunobiological drugs, disease duration and activity were associated with functional capacity variation, in a model with a 37% explanatory capacity. After defining which database variables to use from a theorical model structured with the literature review, we identified that our findings presented common aspects with studies from Europe and North America. A few of the findings were: decrease of functional capacity with pain and disease activity, in female patients and also in those with previously reported immunobiological use. Also relevant were the J-shaped curves related with longer disease duration and worse socioeconomic status. Some hypotheses for the functional capacity scores found were patient adaptability to physical limitations accrued with disease duration and perception that those limitations would be part of a normal ageing process. Though built with data from a population with more than a decade of disease duration, our model included variables commonly associated with the reversible component of functional disability, such as pain and disease activity. In this scenario, tighter control of disease activity would benefit patients and bring the possibility of regaining, at least partially, their functional capacity.