Effect of Formal Education Level on Measurement of Rheumatoid Arthritis Disease Activity

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to joint damage and bone destruction, disability, and increased mortality. The occurrence and outcome of RA is influenced by both genetic and environmental factors. The environmental risk factors for RA include sex, age, smoking, diet, socioeconomic status (SES), and ethnicity. SES is comprised of a combination of factors including education, occupation, and income. A low SES has been associated with a worse clinical outcome and high disease activity in patients with RA [1]. Education, as a composite for SES, is regarded as the best surrogate measure of SES, although the associations between education and diseases are independent of other socioeconomic variables. The formal education level is an easily measured socioeconomic variable and is used as a quick and useful proxy for SES. An inverse association has been demonstrated between the level of education and clinical symptoms in RA patients. A more severe clinical status in RA patients has been associated with a lower formal education level, and this association is not explained by age, sex, clinical setting, smoking history, treatment used, or disease duration [1]. A prospective study showed that RA patients with the lowest formal education level presented with higher Health Assessment Questionnaire scores, higher tender and swollen joint counts, and more X-ray damage [2]. Over a follow-up period of 5 to 8 years, those with the lowest education level showed a tendency for a worse outcome [2]. A Sweden study demonstrated that patients with RA and lower education and occupation had higher hospitalization rates compared to the general population [3]. Morbidity and mortality rates in patients with RA have also been reported to vary significantly according to the level of formal education [4]. Associations between a low formal education level and increased morbidity and mortality have been well established in patients with RA [4]. A low formal education level is a significant predictor of premature mortality in patients with RA, and dose-response relations have been noted for formal education as a predictor of mortality [5]. A long-term cohort study in which the participants were followed for up to 35 years showed that low education was a significant risk factor for mortality among RA patients [6]. The association between lower formal education level and increased morbidity and mortality due to RA was not explained simply by age or disease duration. Previous studies have shown an association between low formal education and an increased risk of RA with mixed results. A population-based case-control study found that subjects without a university degree were at a significantly higher risk for developing RA compared to individuals with a university degree [4]. A study revealed that the RA prevalence rate decreased with higher education in the Korean population, and the difference was statistically significant even after controlling for sex and age [7]. A population-based study in Norway found an inverse association between longer education and risk of RA, but this association was not statistically significant after adjusting for age, sex, marital status, body mass index, employment status, and baseline smoking [8]. Further studies are needed to explore the association between formal education and RA risk.