Preoperative pulmonary function tests before low-risk surgery in Japan: a retrospective cohort study using a claims database

Routine preoperative pulmonary function tests (PFTs) are not recommended prior to low-risk surgery because their prognostic value is limited. However, only a few studies have assessed the utilization of healthcare resources regarding preoperative PFTs in a real-world setting. Here, we aimed to assess the prevalence and determinant factors of preoperative PFTs before low-risk surgery in Japan.

In this retrospective cohort study, we used the nationwide insurance claims databases. Patients who underwent low-risk surgeries under general anesthesia between April 1, 2012, and March 31, 2016, were included. The primary outcome was the receipt of PFTs within 60 days before an index surgery. We performed descriptive analyses to estimate the rates of preoperative PFTs annually starting in 2012, and examined the associations between patient- and institutional-level factors and preoperative PFTs using multilevel logistic regression analyses.

The cohort included 9495 procedures (8866 patients) at 1487 institutions. Preoperative PFTs were conducted before 71.8% of the procedures. The temporal trend of preoperative PFTs remained constant from 72.4% in 2012 to 72.2% in 2015. Multilevel regression analysis revealed that preoperative PFTs were associated with older age, number of beds at a medical facility, and inpatient procedures. The median institutional-specific proportion of PFTs was 75.0% (interquartile range, 14.3-100%) with wide inter-institutional variation.

Our analysis found that preoperative PFTs were performed before 72% of low-risk surgeries under general anesthesia. Apart from age, preoperative PFTs were determined primarily by non-medical factors. Additionally, we observed substantial institutional variation in the use of preoperative PFTs.