RESUMEN
BACKGROUND: To develop and assess a prediction model for polymyalgia rheumatica (PMR) relapse within the first year of glucocorticoid (GC) treatment. METHODS: A retrospective PMR cohort (clinical diagnosis) from a rheumatology department was used. All visits > 30 days after starting GC treatment and with > 2.5 mg/day oral prednisolone were used as potential relapse visits. Often used relapse criteria (1) rheumatologist judgement, (2) treatment intensification-based relapse) were assessed for agreement in this cohort. The proportion of patients with treatment-based relapse within 1 and 2 years of treatment and the relapse incidence rate were used to assess unadjusted associations with candidate predictors using logistic and Poisson regression respectively. After using a multiple imputation method, a multivariable model was developed and assessed to predict the occurrence (yes/no) of relapse within the first year of treatment. RESULTS: Data from 417 patients was used. Relapse occurred at 399 and 321 (of 2422) visits based on the rheumatologist judgement- and treatment-based criteria respectively, with low to moderate agreement between the two (87% (95% CI 0.86-0.88), with κ = 0.49 (95% CI 0.44-0.54)). Treatment-based relapse within the first two years was significantly associated with CRP, ESR, and pre-treatment symptom duration, and incidence rate with only CRP and ESR. A model to predict treatment intensification within the first year of treatment was developed using sex, medical history of cardiovascular disease and malignancies, pre-treatment symptom duration, ESR, and Hb, with an AUC of 0.60-0.65. CONCLUSION: PMR relapse occurs frequently, although commonly used criteria only show moderate agreement, underlining the importance of a uniform definition and criteria of a PMR specific relapse. A model to predict treatment intensification was developed using practical predictors, although its performance was modest.
RESUMEN
Guidelines on management of polymyalgia rheumatica (PMR) recommend early introduction of methotrexate (MTX), especially in patients with worse prognosis, although evidence on clinical efficacy of MTX in PMR is limited. Our objective was to assess MTX efficacy in real-world PMR care. Retrospective data of newly diagnosed PMR patients who started MTX were compared to control patients in whom MTX was not started at the first flare. Main outcomes were number of flares per year (Poisson regression) and weighted daily glucocorticoid (GC)-dose (linear regression), and flare incidence rate ratio in the MTX group only. 240 patients were selected; 39 patients in the MTX group and 201 in the control group. The yearly incidence rate ratio of flares in the MTX versus control group was 0.80 (95% CI 0.45-1.42). The yearly flare rate was 1.22 before and 0.43 after MTX initiation, resulting in an incidence ratio of 0.35 (95% CI 0.23-0.52). Adjusted time weighted daily GC dose was higher in the MTX versus control group (ratio 1.37, 95% CI 1.04-1.80). No clear effect of MTX on flares was found and time weighted daily GC dose was higher, possibly due to residual confounding by indication. However, the clearly reduced flare rate after MTX start might be suggestive for a beneficial effect of MTX.