The effect of antireaction medications on the association between periodontitis and leprosy reactions: An important methodological issue in periodontal medicine

Background: The treatment of leprosy reactions (LRs) involves thalidomide, corticosteroids, and other immunomodulatory medications. This study evaluated the effect of these treatments on the association between periodontitis and LRs, as well as factors associated with LRs.Methods: This case–control study was conducted on 283 individuals followed at a leprosy outpatient clinic in Brazil. The case group was comprised of 158 individuals presenting type 1 or type 2 LRs, and the control group of 125 leprosy individuals without reactions. A complete oral examination was performed to diagnose periodontitis, the independent variable. Antireaction medication used was collected from medical records, and participants were classified according to the use of prednisone and/or thalidomide, time of use, or non‐use of medication. Socioeconomic–demographic, clinical, and lifestyle covariables were collected by interview. Unconditional logistic regression analysis by subgroups evaluated the effect of antireaction medication on the association between periodontitis and LRs, estimating the odds ratio with a 95% confidence interval (OR; 95% CI).Results: A relationship between periodontitis and LRs was observed only in the subgroup using the association prednisone and thalidomide: ORadjusted = 0.32; 95% CI = 0.11–0.95. Conversely, more severe periodontal clinical parameters were observed in cases versus controls. Several socioeconomic, health conditions, and lifestyle factors were associated with the presence of LRs.Conclusions: Although periodontal disease indicators were worse among the cases, the findings showed a negative relationship between periodontitis and LRs in individuals receiving associated prednisone and thalidomide. These medications appear to influence the inflammatory cascade between diseases, modifying and masking the manifestations of periodontitis.