Feasibility of Pulmonary Function Testing at Baseline Prior to Pediatric Hematopoietic Stem Cell Transplantation (HSCT) Patients

Abstract

Rationale: Pulmonary complications are common and significantly contribute to morbidity and mortality following pediatric hematopoietic stem cell transplantation (HSCT), and pulmonary function testing (PFT) is critical for early detection and treatment. This study evaluates the impact of a multidisciplinary respiratory-HSCT service on improving technically acceptable PFTs before transplantation. Methods: We retrospectively analyzed all PFTs from children undergoing HSCT at the Queensland Children's Hospital over 5 years prior to the COVID-19 pandemic (2015-2019 inclusive). Quality control grading was performed on pre-HSCT PFTs identified from existing electronic medical databases [spirometry (if ≥5 years), body plethysmography (if ≥8 years) and gas transfer (DLCO) (if ≥8 years)] using ATS/ERS criteria by an experienced pediatric respiratory scientist (KS). The same approach was used within a post-COVID 12-month period (August 2023-July 2024 inclusive) with multiple breath washout (MBW) scored by an experienced physician (PDR). Success rates between cohorts were compared using Fisher's exact test. Results: Between 2015-2019, 150 subjects received HSCT [median (range) age 5.49 (0.01-18.2 years) years] with 53% (79/150) eligible for any PFTs (i.e. ≥5 years). 86% of eligible patients (68/79) attempted baseline PFT [45% (68/150) of total cohort receiving HSCT]. Technical acceptability was achieved in 63% (50/79) for spirometry, 77% (46/60) for DLCO, and 70% (42/60) for body plethysmography, such that 73% (58/79) and 46% (36/79) achieved this for ≥1 or all eligible PFT tests [39% (58/150) and 24% (36/150) of total HSCT cohort], respectively. In 2023-24, of the 40 subjects receiving HSCT [5.15 (0.85-17.8) years], eligibility for PFTs (i.e. ≥3 years given MBW availability) increased to 65% (26/40) with 92% (24/26) attempted. Technical acceptability was achieved in 75% (15/20) for spirometry, 88% (15/17) for DLCO, 82% (14/17) for body plethysmography and 100% (23/23) for MBW, such that 88% (23/26, p=0.18 vs. 2015- 19) and 69% (18/26, p=0.044 vs. 2015-19) achieved this for ≥1 or all eligible PFT tests [58% (23/40, p=0.047 vs. 2015-19) and 45% (18/40, p=0.017)] vs. 2015-19 of total HSCT cohort), respectively. Conclusions: Reliance of conventional lung function tests resulted in only half of subjects being eligible for baseline PFT prior to HSCT in our historical cohort. Of those eligible, only 73% achieved technical acceptability in at least one PFT measure and 46% in all eligible tests. Incorporation of MBW into pre-HSCT PFT screening as part of a formal respiratory-HSCT service increased not only eligibility, but also the proportion with a technically acceptable estimate of pre-HSCT lung function.