OBJECTIVE: To analyze the risk factors of hypophosphatemia in patients with acute respiratory distress syndrome (ARDS). METHODS: A retrospective case-control study was conducted. The clinical data of the patients with ARDS admitted to Yanbian University Affiliated Hospital from January 2018 to October 2022 were collected. According to the 1-day serum phosphorus level after intensive care unit (ICU) admission, the patients with normal (0.80-1.45 mmol/L) or elevated (>
1.45 mmol/L) serum phosphorus levels were included in the non-hypophosphatemia group, while those with phosphorus levels lower than 0.80 mmol/L were included in the hypophosphatemia group. The differences in the inflammatory indicators [neutrophils percentage (NEU%), neutrophil count (NEU), lymphocyte count (LYM), high-sensitivity C-reactive protein (hs-CRP)], proteins [total protein (TP), albumin (Alb), prealbumin (PA)], blood lactic acid (Lac), neutrophil/lymphocyte ratio (NLR), neutrophil/albumin ratio (NAR), and blood lactic acid/albumin ratio (L/A) at 1, 2, 4, 6 and 8 days after ICU admission were compared between the two groups. The partial correlation method was used to analyze the correlation between the 1-day serum phosphorus level after ICU admission and the above indicators. Multivariate Logistic regression analysis was adopted to explore the risk factors of hypophosphatemia in patients with ARDS. RESULTS: All 110 patients were enrolled in the final analysis, among which there were 56 cases in the hypophosphatemia group and 54 cases in the non-hypophosphatemia group. At 1 day and 2 days after ICU admission, NEU% in the hypophosphatemia group were significantly higher than those in the non-hypophosphatemia group (1 day: 0.87±0.08 vs. 0.82±0.12, 2 days: 0.87±0.05 vs. 0.83±0.11, both P <
0.05). As the ICU admission time prolonged, LYM in the hypophosphatemia group was basically on the rise, and NEU%, hs-CRP, and NLR were first decreased and then increased. At 1 day after ICU admission, TP, Alb and PA in the hypophosphatemia group were significantly lower than those in the non-hypophosphatemia group [TP (g/L): 52.96±8.42 vs. 56.47±8.36, Alb (g/L): 29.73±5.83 vs. 33.08±7.35, PA (g/L): 69.95±50.72 vs. 121.50±82.42, all P <
0.05]. As the ICU admission time prolonged, TP and Alb in the hypophosphatemia group were basically showed a trend of first decreasing and then increasing, but at 8 days, Alb was still lower than that at 1 day, and PA basically showed an upward trend. In the non-hypophosphatemia group, the change trends of TP and Alb were consistent with those in the hypophosphatemia group. Lac and L/A both showed a downward trend in the two groups. Partial correlation analysis showed that 1-day serum phosphorus level after ICU admission was significantly negatively correlated with NEU% and hs-CRP (r value was -0.229 and -0.286, respectively, both P <
0.05), and significantly positively correlated with LYM and PA (r value was 0.231 and 0.311, respectively, both P <
0.05). Multivariate Logistic regression analysis showed that 1-day NEU% [odds ratio (OR) = 0.932, 95% confidence interval (95%CI) was 0.873-0.996, P = 0.038] and Alb (OR = 1.167, 95%CI was 1.040-1.308, P = 0.008) were the independent risk factors for hypophosphatemia in ARDS patients. CONCLUSION: NEU% and Alb at 1 day after ICU admission are independent risk factors for hypophosphatemia in patients with ARDS.