Cause analysis of conversion to biologics in spondyloarthritis patients with poor response to conventional treatment

Objective We sought to investigate the reasons why spondyloarthritis (SpA) patients failed to respond to non-steroidal anti-inflammatory drugs (NSAIDs) and conventional synthetic disease-modifying antirheumatic drugs (cDMARDs) and the influences of different initial cDMARDs on the likelihood of a switch to biologics. Methods SpA patients were divided into a conventional drug maintenance group and a biologics conversion group to determine the causes of conversion to biologics. Then, we divided all patients into three groups according to different initial cDMARDs, NSAID monotherapy, NSAID + (sulfasalazine or thalidomide) double combination, and NSAID + sulfasalazine + thalidomide triple combination therapy groups, to clarify the influence of initial treatment on later conversion to biologics. Results This study includes 202 patients, including 97 patients in the conventional drug maintenance group and 105 patients in the biologics conversion group. The mean age of the conventional drug maintenance group was higher than that of the biologics conversion group (40.8 ± 14.3 vs. 33.8 ± 12.3 years, P < 0.05). Uveitis (OR 5.356, P < 0.05) is positively correlated with conversion to biological therapy, while age (OR 0.940, P < 0.05) is negatively correlated. The proportion of NSAID monotherapy, double combination, and triple combination groups converted to biological agents was 80%, 51.1%, and 23.2%, respectively ( P < 0.05). Conclusion Age and uveitis are related to conversion to biologics therapy. The early combination of sulfasalazine and thalidomide with NSAIDs may lower the probability of conversion to biologics therapy in the later stage and offer a new option for patients with limited use of biologics in SpA patients. Key Points • Patients’ move to biologics may be caused mostly by inadequate disease control by conventional oral medications. • Regardless of axial vs. peripheral joint involvement, combination drug therapy was superior to single drug therapy in controlling SpA and decreasing the probability of conversion to a biological agent. • For SpA patients who are not candidates for biologics due to contraindications or other reasons, early combination application of NSAIDs, sulfasalazine, and thalidomide may be a new choice.