Serum levels of Krebs von den Lungen‐6 as a promising marker for predicting occurrence and deterioration of systemic sclerosis‐associated interstitial lung disease from a Chinese cohort

AIM: A prospective and longitudinal study to investigate the correlations between Krebs von den Lungen‐6 (KL‐6) serum levels and systemic sclerosis associated with interstitial lung disease (SSc‐ILD). METHOD: Blood samples of baseline and the time point at 2 years follow‐up intervals were collected for the measurement of serum KL‐6 levels. The baseline clinical, laboratory characteristics, and incidence density of newly diagnosed ILD during the follow up were compared between SSc patients with elevated serum KL‐6 levels (KL‐6 > 500 U/mL) and those with normal KL‐6 levels (KL‐6 ≤ 500 U/mL) at baseline. Further, we explored the association between serum KL‐6 and deterioration of ILD measured by lung function parameters during follow‐up of 2 years. RESULTS: Patients with elevated baseline serum KL‐6 had a significant tendency to have disappearance of the finger pad. The incidence density of new‐onset ILD in SSc patients with elevated baseline serum KL‐6 and those with normal baseline serum KL‐6 was 1.33% and 0.51%, respectively. Among the mild lung injury group, the incidence density of ILD deterioration in SSc patients with elevated baseline serum KL‐6 and those with normal serum KL‐6 was 1.2% and 0.74%, respectively. CONCLUSION: Serum KL‐6 level correlates with the clinical manifestations of microvascular injury. Baseline elevated serum KL‐6 may predict deterioration of lung function of SSc‐ILD patients with mild lung injury.