ABSTRACT

Idiopathic inflammatory myopathies (IIM) are a group of connective tissue diseases that are characterized with proximal muscle inflammation and immune mediated muscle damage. Compared to the general population, both malignancy and mortality rates are found to be higher in IIM patients. The aim of our study was to define the predictive factors for mortality and to evaluate the types and frequencies of concomitant malignities in IIM patients.

A retrospective evaluation was conducted in 53 patients who were diagnosed with IIM using 1975 Bohan-Peter criteria in university hospital rheumatology department between January 1998 and January 2020. The clinical and laboratory findings, malignancy status and prognostic factors for mortality were analyzed for the patients.

Among the 53 patients (32 women, 21 men), the mean age was 55.24±16.12 years, the mean age of myopathy diagnosis was 44.45±17.62 years. When the subgroups of myositis were analyzed, 27 patients (50.9%) had dermatomyositis and 23 patients (43.4%) had polymyositis. The most frequent clinical finding was fatigue with 77.2%. Steroid usage rate was 98.1% and azathioprine usage rate was 34% among patients. Malignancy frequency was 13% (n=7) (2 nasopharyngeal cancer, 2 colon cancer, 1 non-small cell lung cancer, 1 breast cancer and 1 pancreas cancer) and the age of patients with malignancy and myositis was significantly higher (p=0.03, p=0.02 respectively). When the mortality frequency was evaluated by different parameters, it was found that gender, disease duration and malignity preexisting myositis were statistically significant parameters. The most frequent mortality cause was malignancy. Cumulative survival rate in our cohort was 80.75% in 5 years and 72.68% in 10 years.

As a result, the frequencies of mortality and malignancy in our patients with IIM were generally similar to those in the literature. The most important factors affecting life expectancy and mortality were advanced age at diagnosis and the presence of malignancy.