# Factors associated with readmission risk in patients with HIV stratified by BMI: a hospital-based retrospective matched cohort study

## TL;DR

This study finds that BMI influences which factors predict hospital readmission risk in people with HIV, suggesting tailored interventions based on weight status.

## Contribution

The study identifies BMI as an effect modifier in readmission risk factors for people with HIV, revealing distinct risk profiles for underweight versus normal/overweight individuals.

## Key findings

- Underweight PWH had higher readmission rates compared to normal/overweight PWH.
- Unemployment and lower nadir CD4+ count were key risk factors for underweight PWH.
- For normal/overweight PWH, unemployment and longer time since diagnosis increased readmission risk.

## Abstract

The role of body mass index (BMI) as an effect modifier for readmission risk in people with HIV (PWH) remains underexplored.

To compare factors associated with two-year all-cause readmission in PWH, stratified by baseline BMI.

A retrospective matched (1:1 by age/sex) cohort study was conducted at a major public infectious diseases hospital in Shenzhen, China, serving a diverse urban population including migrants and low-income individuals. Adults admitted (Jan–Jun 2020) were stratified into underweight (BMI < 18.5 kg/m², n = 80) and normal/overweight (BMI 18.5–<28 kg/m², n = 231) groups. Multivariable logistic regression and ROC analysis were performed within each stratum.

The readmission rate was higher in the underweight group (61.3% vs. 46.8%, p = 0.023). For underweight PWH, unemployment (adjusted Odds Ratio [aOR] = 8.11, 95% CI 1.82–36.16) and lower nadir CD4 + count (aOR = 0.994 per cell/µL decrease, 95% CI 0.989–0.999) were independent risk factors. For normal/overweight PWH, unemployment (aOR = 2.21, 95% CI 1.12–4.38) and longer time since diagnosis (> 5 vs. 0–1 years, aOR = 4.28, 95% CI 2.02–9.07) were risk factors, while being widowed/divorced was protective (aOR = 0.30, 95% CI 0.10–0.86). Predictive models showed good to excellent accuracy (AUCs: 0.820 and 0.748, respectively).

Risk factors for readmission differ markedly by baseline BMI, confirming its role as an effect modifier. Interventions should be tailored: integrated nutritional and immunological support for underweight PWH, and chronic disease management with attention to social determinants for others.