Relationship of phase angle with postoperative pneumonia and survival prognosis in patients with esophageal cancer: A retrospective cohort study.

OBJECTIVES

Phase angle (PhA), derived from bioelectrical impedance analysis (BIA), is an indicator of cell membrane health. Low PhA values reflect poor cellular function and low muscle mass. However, consensus regarding the appropriate cutoff value of PhA remains insufficient, and its impact on outcomes after esophagectomy in patients with esophageal malignancies is not well studied. We aimed to investigate whether preoperative PhA is associated with postoperative complication risk and survival prognosis and whether PhA decrease during the surgical preparation period is a prognostic factor in patients with esophageal cancer.

METHODS

This retrospective cohort study analyzed data from 194 patients who had undergone esophagectomy for esophageal malignancies. A PhA measured several days before surgery, with cutoff values of 5.0° for men and 4.2° for women, was used. The relationship between postoperative pneumonia and clinicopathological factors and between low PhA and postoperative outcomes and survival prognosis was investigated. The preoperative PhA decline and survival prognosis were analyzed in 134 patients whose PhA was measured twice before surgery.

RESULTS

Overall, 93 and 101 patients were classified into the low and high PhA groups, respectively. A multivariate analysis showed that a serum albumin level lower than 3.5 g/dL and low PhA were independent risk factors for pneumonia (odds ratio [OR] = 3.40, P = 0.03; OR = 3.42, P = 0.03, respectively). The low PhA group exhibited significantly higher intraoperative fluid balance (6.7 versus 6.0 mL/kg/h, P = 0.01) and a higher proportion of patients who failed to achieve early mobilization on the first postoperative day (46 versus 32%, P = 0.04) than did the high PhA group. Multivariate analysis using a Cox proportional hazards model revealed that low PhA was a poor survival prognostic factor, independent of the clinical stage of esophageal cancer (hazard ratio = 2.61, P < 0.01). In patients whose PhA was measured twice preoperatively, a decrease in PhA during the preoperative period was a significant indicator of poor survival (hazard ratio = 2.59, P < 0.01). The group with a decrease in PhA during the preoperative period had significantly fewer steps than the group with an increase in PhA (6220 ± 2880 versus 8200 ± 2850, P < 0.01).

CONCLUSIONS

Low PhA was a risk factor for postoperative pneumonia in patients who had undergone esophagectomy and was associated with poor survival prognosis. A decrease in PhA during the preoperative period was a significant poor prognostic factor. Increasing physical activity before surgery may lead to an increase in PhA. Thus, it is important to measure and evaluate PhA changes sequentially in patients with esophageal cancer.