Objective: To analyze the predictive factors and the unfavourable prognostic factors of interstitial lung disease (ILD) in patients with polymyositis (PM)/dermatomyositis (DM).
Methods: The clinical data were collected from 87 inpatients with DM or PM, who were admitted to Shanghai Changhai Hospital from January 1997 to November 2006. The patients were divided into an ILD group and a non-ILD group. The clinical feature, incidence and prognosis of ILD were retrospectively analyzed. The clinical and laboratory data were analyzed by using the SPSS 13.0 software. The t-test and rank-sum test were used, depending on the measurement data. The enumeration data were analyzed with chi-square test. Logistic regression and Kaplan-Meier survival curve were used to analyze the correlative and prognostic factors of interstitial lung disease (ILD) in patients with PM/DM.
Results: The incidence and mortality of ILD in PM/DM patients were 46% (40/87) and 40% (16/40), respectively. Compared with the non-ILD group, the age in the ILD group was markedly older [(54 +/- 13) years vs (45 +/- 18) years], and the percentages of fever (21/40 vs 7/47, chi2 = 14.00, P < 0.01), dysphagia (16/40 vs 8/47, chi2 = 5.71, P < 0.05), arthralgia (26/40 vs 9/47, chi2 = 18.89, P<0.01), Gottron's rash (14/40 vs 2/47, chi2 = 13.61, P <0.01) and heart impairment (26/40 vs 14/47, chi2 = 10.28, P <0.01) were significantly higher in the ILD group. The levels ofLDH [(472 +/- 285) IU vs (310 +/- 238) IU, t =2.86, P<0.01], ESR [(44 +/- 24) mm/1 h vs (26 +/- 24) mm/l h, t = 3.19, P <0.01] and immunoglobulin G [(18 +/- 9) g/L vs (14 +/- 5) g/L, t = 2.31, P <0.05] were statistically different between the two groups. By multivariate nonparametric logistic regression analysis, Gottron's rash, arthralgia, fever, and > or = 40 years of age were identified as predictors with relative risk ratio of 12.048, 7.812, 6.329 and 5.236 respectively. The unfavourable prognostic factors of ILD were Gottron' s rash (chi2 = 5.35, P <0.05), cardiac impairment (chi2 = 5.68, P < 0.05) and pulmonary fibrosis (chi2 = 5.42, P <0.05) by survival analysis.
Conclusion: The occurrence of ILD in PM/ DM patients was closely correlated to Gottron's rash, age > or = 40 years, arthralgia and fever. Gottron's rash, heart impairment and pulmonary fibrosis were poor prognosis factors of PM/DM patients complicated with ILD.