Background/Purpose: Low back pain (LBP) is ubiquitous and estimated to affect 26% of Americans in any 3 month period. Why would rheumatoid arthritis patients be any different? We noted improvement in chronic LBP among patients using JAK inhibitors (JAKinibs) in a prospective program.

Methods: Sequential RA patients over age 40 were first educated, to explain that RA is not a typical cause chronic LBP. Patients with over 3 months of chronic LBP with or without radiculopathy, then signed informed consent and completed questionnaires. At baseline, patients scored > 6 on the LBP intensity score (out of 11 maximum score), a disability score of 12 (max score 24), and a response of fair, poor, or very poor in the Leikert patientÕs global assessment (PGA).These responses were specific to the back. Often LBP had been present for a decade proceeding RA.Excluded for thirty days prior and during the study were narcotics, corticosteroids, gabapentin, pregabalin, anti-depressants, acetaminophen, and muscle relaxants. All patients had moderate to severe RA where JAKinibs were appropriate treatment. Patients answered questionnaires specific to LBP every 2 weeks for a 12 week period.They were randomized by birth year. This phase 1 study was single blind.All assessments of LBP were by the patient (blinded to therapy). This was a phase 1 exploratory trial for improvement in LBP with JAKinhibs. 

Results: 74 patients enrolled; 37 each to JAKinhib and placebo for 12 weeks.There were 74% women, average age 59.6 years, BMI 27.4, Caucasian 58%, Hispanic 41% and Asian 1%. Despite no differences at baseline, chronic LBP in the JAKinib group improved compared to placebo. The pain score decreased 2.1 (31%), p< 0.01; the disability score improved 3.9 (21%), p< 0.01; the PGA improved 0.8 (19%), p< 0.01; and stiffness in the back improved 0.7 (16%), p<0.02. Originally, patients reported 4.5 lost work hours due to chronic LBP, out of a 40 hour week.The JAKinib group reported no loss in work hours after 12 weeks.The improvements began at 2 weeks and were sustained during the 12 week observation period.

Conclusion :This is a proof of concept trial evaluating JAKinhibs for the treatment of LBP. In the past decade, many trials have attempted to find LBP therapy among anti-inflammatory and anti-cytokine therapies, including a study with etanercept as an epidural injection therapy. None have been found effective. In recent large RA trials where JAKinibs are being evaluated for the treatment of RA, adverse events of LBP were less frequent in the JAKinhibs groups than the placebo. Given that LBP is ubiquitous and RA patients are susceptible to mechanical LBP, we prospectively tracked in randomized patients, pain, disability, PGA, stiffness and work loss. In each category, the JAKinhib group improved compared to placebo in LBP. Perhaps this immunotherapy JAKinib, can provide mild to moderate benefit in the treatment of chronic LBP.