多發性肌炎與皮肌炎患者併發間質性肺病時序與臨床預後之分析

Interstitial lung disease in polymyositis/dermatomyositis: association between the onset of interstitial lung disease and clinical outcome

目的：探討台灣地區，多發性肌炎（polymyositis, PM）與皮肌炎（dermatomyositis, DM）合併間質性肺病（interstitial lung disease, ILD）之患者，其預後因子與存活之分析。方法：本回溯性研究分析於1999至2008年間，同時合併PM/DM與ILD，而在國立台灣大學附設醫院接受治療之病患病歷資料。結果：分析285名PM/DM患者，發現有43名同時合併ILD（15%）。依發生ILD與PM/DM之時序，可分為三組病人：（1） ILD發生在PM/DM診斷之前（n = 8），（2） ILD與PM/DM同時診斷（n = 19），（3） ILD發生在PM/DM診斷之後（n = 16）。我們分析發現，第3組病人年紀較輕、併發間質性肺病時所用的類固醇劑量較高，表示第3組的病人可能疾病活性也較高。並且相較於第1組（75%）有較差的存活率（37%）。合併ILD之PM/DM病患平均死亡率為44%，然而在第三組的病人就高達63%（10/16）。三組大部分病患的死亡皆發生在診斷ILD的一年內死亡。結論：同時合併ILD之PM/DM病患通常臨床預後較差，並且死亡率高。而PM/DM患者發生ILD之時序，可能與其預後相關。PM/DM之後才發生的ILD，也許可作為預後不佳之重要指標。

Objective: We assessed the clinical outcome and prognostic predictors in patients with polymyositis (PM)/dermatomyositis (DM) and interstitial lung disease (ILD) in Taiwan. Methods: Forty-three patients with PM/DM and ILD were enrolled from January 1999 to July 2008 at the National Taiwan University Hospital and their clinical data were reviewed and analyzed. Results: The proportion of ILD in our PM/DM patients was 15% based on high resolution computer tomography or pulmonary function test results. All patients were classified into 3 subgroups according to the onset sequence of ILD: Group 1 was comprised of patients in whom ILD was diagnosed preceding PM/DM (n = 8), Group 2 included patients in whom ILD was diagnosed concomitantly with PM/DM (n = 19), and Group 3 consisted of patients in whom ILD was diagnosed after PM/DM (n = 16). The patients in Group 3 were younger (p=0.04), and had received more corticosteroid medications (p=0.01) when ILD was diagnosed, which indicated more severe disease activity in Group 3 patients. These patients were also associated with a significantly decreased survival rate (37%) compared to those with ILD preceding PM/DM (75%; p=0.032). The overall mortality rate in patients with PM/DM and ILD was approximately 44%, however, the mortality rate in Group 3 patients was as high as 63% (10/16). Most mortality occurred within 1 year after the diagnosis of ILD among the 3 groups. Conclusion: PM/DM patients with ILD are associated with poor clinical outcome and a high mortality rate. The onset of ILD and PM/DM may be associated with prognostic outcome in these patients. PM/DM onset followed by ILD development may be an important indicator for poor prognosis.