Admission weight-for-age defined underweight and 18-month clinical outcomes in infants with cholestasis: a five-year retrospective cohort study

Growth impairment is common in infantile cholestasis. Weight-for-age identifies underweight but does not capture all nutritional deficits or distinguish acquired depletion from other causes of poor growth. To describe admission WAZ-defined underweight and associated anthropometric deficits, and examine associations with in-hospital and 18-month clinical outcomes. This retrospective cohort included 696 infants with recorded admission ages of 1–12 months and cholestasis during 2019–2023. Underweight was defined as WAZ < − 2. Complementary anthropometry was described separately. Logistic and gamma regression examined admission and hospital outcomes. Complete-case Cox regression examined the 18-month composite; component risks and paired growth changes were reported separately. Underweight occurred in 163/696 infants (23.4%); 47.2% had wasting and 52.8% had stunting. Among comparison infants, 7.3% had wasting and 10.5% had stunting. Prematurity, small-for-gestational-age status and the low-intake flag were associated with underweight. Outcomes were ascertained in 628 infants. Readmission occurred in 42.3% versus 22.0%, and transplantation or death in 14.1% versus 4.9%. The complete-case Cox sample comprised 593 infants and 183 events; underweight was associated with the composite (adjusted hazard ratio 1.70, 95% CI 1.22–2.37). In 96 initially underweight infants with paired measurements, mean WAZ increased by 1.58 units. Much recorded morbidity was prevalent or of uncertain onset. WAZ-defined underweight was associated with adverse outcomes and greater healthcare use. WAZ ≥ − 2 did not exclude other deficits. Paired growth improvement remains subject to regression to the mean and selective follow-up.