Endocrine, immune, and disease dynamics in a patient with rheumatoid arthritis during flare and medication change

Rheumatoid arthritis (RA) is a chronic autoimmune disease of widely unknown etiology and pathophysiology. In this integrative single-case study on a patient with RA, we had the unique opportunity to closely monitor the individual dynamics of endocrine, immune and disease variables during a naturally occurring flare-up and subsequent medication change. The female RA patient collected her entire urine over 30 days in 12-h intervals (60 consecutive measurements in total). Subsequently, interleukin-6 (IL-6), orosomucoid-2, cortisol (ELISA), neopterin and creatinine (HPLC) levels were determined in the urine samples. Further, each morning and evening, the patient completed the DIARI, a set of questionnaires on variables such as subjective pain, subjective RA disease activity and emotional states. Once a week, besides an online video interview, the patient had an appointment at her rheumatologist, in which several indices of RA disease activity were determined: SDAI, CDAI and DAS28. From these data various time series were constructed for statistical analysis. RA disease state increased from low to high activity during the first 12 study days. Thereupon, the medication was changed, which proved effective in reducing RA disease activity. However, the levels of urinary neopterin, urinary orosomucoid-2 and urinary IL-6 did not show any response, neither to the increasing disease activity nor the medication change. The patient's daily reports on pain, RA disease activity and emotional states, however, mirrored the course of the rheumatologic indices. For the patient studied, urinary neopterin, urinary orosomucoid-2 and urinary IL-6 levels did not represent adequate biomarkers of short-term variations in RA disease activity. Patient-reported outcomes on the other hand might be a useful tool in the ambulatory and longitudinal monitoring of RA.