A new clinical rule is particularly useful for physicians who do not feel sufficiently experienced in performing joint examination to assess synovitis. This rule has demonstrated efficacy in identifying inflammatory arthritis, according to a study recently published in BMJ Open.

This split-sample validation and derivation study included 1288 participants, all of whom visited the Leiden Early Arthritis Recognition Clinic between 2010 and September 2015. Screening was performed twice weekly from 2010 to 2014, then once weekly beginning in 2014. Physicians who had referred participants to the clinic suspected inflammatory arthritis, but were unable to confirm it. Logistic regression was used to examine the relationship between clinical characteristics and inflammatory arthritis in 644 participants, whereas split-sample validation was used for the results of the other 644. From these results, a clinical rule was developed that produced a score between 0 and 7.5 indicating inflammatory arthritis.

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Rheumatologists identified inflammatory arthritis in 41% of participants. The derivation dataset, analyzed using univariate analysis, showed associations between inflammatory arthritis and difficulty forming a fist, joint swelling (self-reported), between 1 and 3 painful joints, stiffness <1 hour in the morning, fewer than 6 weeks of symptom duration, male gender, and age of at least 60 years.

These symptoms were compiled via multivariable analysis into a simplified rule. Derivation of this rule resulted in an area under the receiver operator characteristic curve (AUC) of 0.74 (95% CI, 0.70-0.78), whereas validation gave an AUC of 0.71 (95% CI, 0.67-0.75). Simplification of the rule did not have a significant effect on predicted risks. To simulate a primary care setting, repeated tests were performed to examine prognostic power in the case of lower inflammatory arthritis prevalence. For these tests, a 20% prevalence of inflammatory arthritis was set.

The primary limitation to this study was the collection of data in a non-primary care facility, which underscores the need for validation among general practitioners.

The study researchers conclude that “this study developed a clinical rule that supports the identification of patients suspected of having [inflammatory arthritis] by physicians that feel insufficiently experienced in assessment of synovitis by joint examination. We hope the current data are a prelude to a data-driven method that supports [general practitioners] GPs, physicians and other healthcare professionals in decision-making in patients with suspected early [inflammatory arthritis].”

Reference

ten Brinck RM, van Dijk BT, van Steenbergen HW, et al. Development and validation of a clinical rule for recognition of early inflammatory arthritis. BMJ Open. 2018; 8(11):e023552.