Background Firefighters are at high risk for subthreshold and full‐threshold posttraumatic stress disorder (PTSD) due to their frequent exposure to various traumatic events. Although individuals with subthreshold PTSD have increased impairment, often needing treatment, the rates of subthreshold PTSD in firefighters remain unknown. Moreover, there is currently no consensus regarding the definition of subthreshold PTSD. The purpose of this study was to investigate the rates and clinical impairment of subthreshold PTSD according to various definitions in a national sample of firefighters. Methods A total of 45,698 Korean firefighters completed self‐reported questionnaires to assess the severity of PTSD symptoms, suicidal behavior, depression, alcohol use problems, and PTS‐related functional impairment. Six different definitions used in the literature were used to calculate the prevalence rate of subthreshold PTSD. Multivariable linear regression and analysis of variance were performed to identify the relationship of subthreshold PTSD with suicidal behavior, depression, alcohol use problems, and PTS‐related functional impairment. Results The rate of full‐threshold PTSD was 2.63%, and the rate of subthreshold PTSD ranged from 1.79% to 17.98%. The individuals with subthreshold PTSD most commonly failed the D criteria, which included negative alterations in cognition and mood. Regardless of the definition used, subthreshold PTSD was found to be associated with increased suicidal behavior, depression, alcohol use problems, and functional impairment. Conclusions Subthreshold PTSD appears to be equal to or more frequent than full‐threshold PTSD in Korean firefighters and associated with various negative clinical outcomes. Further effort to detect and treat subthreshold PTSD in firefighters may be essential.

Background and Objective Global Lung Function Initiative (GLI) 2012 equations were developed to resolve the age‐related disparity in interpreting spirometry results. Local validation of the equation is needed, especially in Northeast Asian children. This study evaluated the GLI equation in Korean children. Methods Spirometry indices (FEV1, FVC, FEV1/FVC, and FEF25%–75%) and clinical information were gathered from three population‐based birth cohorts. Predicted GLI reference values and z scores of spirometry results were calculated for 1239 healthy children. The mean, standard deviation of z scores were compared with the expected 0 and 1. Probabilities of falling below the lower limit of normal (LLN) (z score: −1.64) were compared with the expected value 5%. GLI z scores were assessed according to low (<−2), normal (≥−2 and ≤2), and high (>2) BMI z score groups. Results Mean z scores significantly differed from 0 for FEV1/FVC in males (mean [95% confidence interval]: 0.18 [0.08, 0.27]) and forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) in females (−0.23 [−0.31, −0.15] and −0.26 [−0.36, −0.16], respectively). The standard deviation was larger than 1 for all variables in males and FVC and FEV1/FVC in females. The probability of falling below the LLN was significantly larger than 5% for FEV1 (12.13% [9.64, 14.77]), FVC (15.86% [13.06, 18.81]), and forced expiratory flow at 25%–75% of forced vital capacity (FEF25%–75%) (7.31% [5.29, 9.49]) in males and FVC (11.91% [9.40, 14.60]) in females. FEV1 and FVC z scores increased across low to high body mass index (BMI) groups, and FEV1/FVC decreased from low to high BMI groups. Conclusion GLI equations marginally differ from real‐world values, which should be considered by pulmonologists in practice or research.