Objective
To determine the prevalence, profile and predictors of infections in an Indian cohort of IIM.
Methods
We reviewed the records of a retrospective cohort of IIM enrolled from consecutive patients following up in the clinic as the observation cohort (OC). A newly diagnosed inception cohort of IIM were followed prospectively as the validation cohort (VC) to confirm observations and compare with the OC.
Results
Among 68 patients in the OC (age 33.4 years, F: M 4.2:1), 37(54.4%) experienced 54 infections, of which 21(38.8%) were major and recurrent infections in 11 patients(16.17%) over 3.08 years. Tuberculosis was the most common infection(12, 22.2%), with predominance of extra-pulmonary forms. Serum protein(OR 0.44), platelets(0.44) at disease onset and daily steroid dose(1.04) predicted major infections on multivariate analysis. A higher daily dose of steroids at first infection correlated with number of recurrent infections. Infection free one-year survival was 73.8%.
Of 70 patients in VC (35.7 years, F: M 3.7:1), three had myositis attributed to an infection. Similar proportion of total(22, 33.3%), major(10, 45.4%) and recurrent(4,18%) infections were recorded. Most common infection was community acquired pneumonia, followed by Tuberculosis with serum albumin(OR 0.25) at disease onset being the only predictor. One-year infection free survival was 64.7%. Those who had a major infection had increased mortality at 1 year with survival of 60% compared with 89.09% in those without.
In both cohorts, a daily prednisone dose >6.25 mg predisposed to major infections.
Conclusion
Major and recurrent infections are common in Indian IIM patients and confer higher risk for future infections and lower survival. Respiratory and atypical bacterial infections such as Tuberculosis occur throughout the disease course.