Association between metabolic overweight/obesity phenotypes and readmission risk in patients with lung cancer: A retrospective cohort study

Abstract

Background: Increased body mass index (BMI) and metabolic abnormalities are controversial prognostic factors of lung cancer. However, the relationship between metabolic overweight/obesity phenotypes and hospital readmission in patients with lung cancer is rarely reported.

Methods: We established a retrospective cohort using the United States (US) Nationwide Readmissions Database (NRD). We included adult patients diagnosed with lung cancer from January 1, 2018 to November 30, 2018 and excluded patients combined with other cancers, pregnancy, died during hospitalization, low body weight, and those with missing data. The cohort was observed for hospital readmission until December 31, 2018. We defined and distinguished four metabolic overweight/obesity phenotypes: metabolically healthy with normal weight (MHNW), metabolically unhealthy with normal weight (MUNW), metabolically healthy with overweight or obesity (MHO), and metabolically unhealthy with overweight or obesity (MUO). The relationship between metabolic overweight/obesity phenotypes and 30-day readmission risk was assessed by multivariable Cox regression analysis.

Findings: Of the 115,393 patients included from the NRD 2018 (MHNW [58214, 50.4%], MUNW [44980, 39.0%], MHO [5044, 4.4%], and MUO [7155, 6.2%]), patients with the phenotype MUNW (6531, 14.5%), MHO (771, 15.3%), and MUO (1155, 16.1%) had a higher readmission rate compared to those with MHNW (7901, 13.6%). Compared with patients with the MHNW phenotype, those with the MUNW (hazard ratio [HR], 1.10; 95% CI, 1.06-1.14), MHO (HR, 1.15; 95% CI, 1.07-1.24), and MUO (HR, 1.28; 95% CI, 1.20-1.36) phenotypes had a higher risk of readmission, especially in men, those without surgical intervention, or those aged >60 years. In women, similar results with respect to readmission were observed in people aged >60 years (MUNW [HR, 1.07; 95% CI, 1.01-1.13], MHO [HR, 1.19; 95% CI, 1.06-1.35], and MUO [HR, 1.28; 95% CI, 1.16-1.41]). We also found increased costs for 30-day readmission in patients with MHO (OR, 1.18; 95% CI, 1.07-1.29) and MUO (OR, 1.11; 95% CI, 1.02-1.20).

Interpretation: Increased BMI and metabolic abnormalities are independently associated with higher readmission risks in patients with lung cancer, whereas increased BMI also increases the readmission costs. Follow-up and intervention method targeting increased BMI and metabolic abnormalities should be considered for patients with lung cancer.

Funding: The National Key Research and Development Program of China (2017YFC1309800).

Keywords: BMI, body mass index; Body mass index; CI, confidence interval; HCUP, Healthcare Cost and Utilization Project; HR, hazard ratio; ICD-10, International Classification of Diseases, 10th Revision; LOS, length of stay; Lung cancer; MHNW, metabolically healthy with normal weight; MHO, metabolically healthy with overweight or obesity; MS, metabolic syndrome; MUNW, metabolically unhealthy with normal weight; MUO, metabolically unhealthy with overweight or obesity; Metabolic abnormality; NRD, Nationwide Readmissions Database; OR, odds ratio; PCS, Procedure Coding System; Phenotype; Readmission.

Figure 1

Readmission in patients with lung cancer with metabolic overweight/obesity phenotypes. (A) In total population and by sex. (B) By surgery. (C) By age. *, The p value of inter-group comparison was less than 0.050. MHNW, metabolically healthy with normal weight; MUNW, metabolically unhealthy with normal weight; MHO, metabolically healthy with overweight or obesity; MUO, metabolically unhealthy with overweight or obesity.

Figure 2

Cox survival curve of 30-day readmission in patients with lung cancer. (A) By metabolic overweight/obesity phenotype. (B) By sex. (C) By surgery. (D) By age. MHNW, metabolically healthy with normal weight; MUNW, metabolically unhealthy with normal weight; MHO, metabolically healthy with overweight or obesity; MUO, metabolically unhealthy with overweight or obesity.