The course of cytokine and chemokine gene expression in clinically suspect arthralgia patients during progression to inflammatory arthritis

Work-related physical strain and development of joint inflammation in the trajectory of emerging inflammatory and rheumatoid arthritis: a prospective cohort study

OBJECTIVES

Rheumatoid arthritis (RA) mainly affects small joints. Despite the mechanical function of joints, the role of mechanical stress in the development of arthritis is insufficiently understood. We hypothesised that mechanical stress/physical strain is a risk factor for joint inflammation in RA. Therefore, we studied work-related physical strain in subjects with clinically suspected arthralgia (CSA) as a risk factor for the presence of imaging-detected subclinical joint inflammation and the development of clinical arthritis/RA.

METHODS

In 501 CSA patients and 155 symptom-free persons' occupation-related physical strain was quantified using the International Standard Classification of Occupations. Contrast-enhanced hand-MRIs were made and evaluated for joint inflammation (sum of synovitis/tenosynovitis/osteitis). CSA patients were followed on RA development. Age relationship was studied using an interaction term of physical strain with age.

RESULTS

The degree of physical strain in CSA is associated with the severity of joint inflammation, independent of educational-level/BMI/smoking (interaction physical strain-age p=0.007; indicating a stronger association with increasing age). Physical strain is associated with higher tenosynovitis scores, in particular. In symptom-free persons, physical strain was not associated with imaging-detected joint inflammation. Higher degrees of physical strain also associated with higher risks for RA development in an age-dependent manner (HR=1.20 (1.06-1.37)/10-year increase in age), independent of educational-level/BMI/smoking. This association was partly mediated by an effect via subclinical joint inflammation.

CONCLUSIONS

Work-related physical strain increases the risk of subclinical joint inflammation and of developing RA. The age relationship suggests an effect of long-term stress or that tenosynovium is more sensitive to stress at older age. Together, the data indicate that mechanical stress contributes to the development of arthritis in RA.

When does obesity exert its effect in conferring risk of developing RA: a large study in cohorts of symptomatic persons at risk

OBJECTIVES

Obesity is a known risk factor for developing rheumatoid arthritis (RA). However, it is unclear whether obesity exerts its risk effect during the asymptomatic or the symptomatic clinically suspect arthralgia (CSA) phase of risk. To improve understanding of the effect of obesity on RA development, we aimed to (1) compare body mass index (BMI) at CSA onset to BMI of the general population and (2) study within CSA patients if obesity increases the risk for progression to RA.

METHODS

1107 symptomatic persons at risk for RA from four cohorts (CSA Leiden, CSA Rotterdam, SONAR and TREAT EARLIER placebo arm) were studied. For the first aim, baseline BMI was compared with age-matched/sex-matched BMI of the general population. Patients were stratified for anticitrullinated protein antibody (ACPA) status. Regarding the second aim, the association between BMI and inflammatory arthritis (IA) development during 2 years was studied with Cox regression analysis within each cohort and via meta-analysis in all cohorts.

RESULTS

CSA patients of all cohorts were more often obese than the general population (respectively 21.9% vs 14.0%, 25.7% vs 14.5%, 26.7% vs 14.5% and 33.3% vs 14.9%, in CSA Leiden, CSA Rotterdam, SONAR, TREAT EARLIER placebo arm). Both ACPA-positive and ACPA-negative CSA patients had a higher frequency of obesity. Within CSA, obesity was not associated with IA development compared to normal weight (pooled effect in meta-analysis of four cohorts HR 1.01 (95% CI 0.93 to 1.08)).

CONCLUSIONS

Obesity is not associated with RA development within CSA patients but BMI has already increased in CSA compared to the general population. Obesity, therefore, presumably exerts its risk effect at an early asymptomatic phase of RA development, rather than being associated with the disease processes that ultimately result in clinical arthritis.

Rheumatoid arthritis prevention in arthralgia: fantasy or reality?

The concept of a 'window of opportunity' in treating a disease assumes the existence of a time frame during which the trajectory of the disease can be effectively and permanently modified. In rheumatoid arthritis (RA), optimal timing of this period is presumed to be during the phase before arthritis is clinically apparent and disease is diagnosed. Several proof-of-concept trials of treatment during the 'arthralgia' phase of RA have been completed in the past 4 years, with the underlying notion that temporary treatment at this stage could prevent the development of RA or induce a sustained reduction in the burden of disease. This Review summarizes the results of these trials and reflects on the outcomes in relation to the patients' perspectives. Overall, the majority of symptomatic at-risk individuals could benefit from a fixed period treatment, even if RA does not develop. Various factors must be taken into consideration when translating these findings into clinical practice. More evidence is needed to target the individuals at highest risk, and additional tools are needed to monitor treatment and guide decisions about whether treatment can be discontinued. Without these tools, there is a paradoxical risk of seemingly increasing the incidence of the disease and prolonging disease duration, which is the opposite of what the concept of intervening in the window of opportunity entails.