Background and aim of the study: The frequency and clinical picture of sarcoidosis are different in Finland and Hokkaido, Japan. The aim of this study was to compare the normalisation rate of chest radiographic changes in patients with biopsy-proven sarcoidosis.
Method: The chest radiographs of 437 Finnish and 457 Japanese patients were used and, for the purpose of this study, double-checked in order to make sure that the interpretations were identical. On a yearly basis the radiographs were classified as normalised, improved, unchanged or deteriorated.
Results: Normalisation of chest radiographs occurred in 73% of the Japanese and 40% of the Finnish patients. The difference between the two series was significant (p < 0.001). Gender, young age, presence or absence of symptoms or extrapulmonary lesions at diagnosis or treatment with corticosteroids did not influence the difference between the two series. Of the 191 Finnish and 309 Japanese patients with initial stage I disease a normal chest radiograph was obtained in 47% of the Finnish and 76% of the Japanese patients (p < 0.001), despite the fact that the Finnish series included patients with erythema nodosum, who had a 59% normalisation rate. Of the 186 Finnish and 125 Japanese patients with initial stage II disease, normalisation of the chest radiographs was seen in 36% of the Finnish and in 73% of the Japanese patients (p < 0.001). No difference in normalisation rate was seen between stage III patients.
Conclusion: The prognosis of pulmonary sarcoidosis in Japanese patients in Hokkaido is significantly better than that in Finland defined as normalisation rate of the chest radiographs.