Intra-abdominal pressure and procalcitonin for prognosis in patients with severe acute pancreatitis: An etiology-based analysis

Table 1 Baseline characteristics of the study participants

Characteristics	Total (n = 245)	Training set (n = 172)	Validation set (n = 73)	P value
Demographics
Age (years), mean ± SD	48.7 ± 15.2	49.5 ± 15.3	47.3 ± 14.8	0.287
Male sex	143 (58.4)	97 (56.4)	46 (63.0)	0.327
Body mass index (kg/m²), mean ± SD	25.3 ± 4.1	25.5 ± 4.3	24.9 ± 3.8	0.302
Etiology
Biliary	123 (50.2)	89 (51.7)	34 (46.6)	0.452
Hypertriglyceridemic	53 (21.6)	35 (20.3)	18 (24.7)	0.437
Alcoholic	46 (18.8)	34 (19.8)	12 (16.4)	0.536
Others/idiopathic	23 (9.4)	14 (8.1)	9 (12.3)	0.298
Disease severity scores, mean ± SD
Acute Physiology and Chronic Health Evaluation II	9.1 ± 3.5	9.3 ± 3.6	8.8 ± 3.3	0.318
Ranson	3.2 ± 1.8	3.3 ± 1.9	3.0 ± 1.6	0.245
Sequential Organ Failure Assessment	2.8 ± 2.2	2.9 ± 2.3	2.5 ± 1.9	0.142
Laboratory parameters
WBC (× 109/L), mean ± SD	15.3 ± 4.7	15.5 ± 4.9	14.8 ± 4.3	0.293
Glucose (mmol/L), mean ± SD	9.7 ± 4.3	9.9 ± 4.5	9.3 ± 3.9	0.324
Serum amylase (U/L), mean ± SD	893 ± 567	914 ± 583	845 ± 526	0.381
Triglycerides in mmol/L, median (IQR)	3.5 (1.7-9.3)	3.6 (1.8-9.4)	3.3 (1.5-8.9)	0.415
C-reactive protein (mg/L), mean ± SD	138.2 ± 92.7	141.3 ± 94.5	131.2 ± 88.4	0.428
Interleukin-6 in pg/mL, median (IQR)	149.5 (76.3-257.8)	153.7 (79.2-264.3)	142.1 (71.5-241.6)	0.367
Intra-abdominal pressure (mmHg), mean ± SD	12.6 ± 4.7	12.8 ± 4.8	12.1 ± 4.4	0.294
Procalcitonin in ng/mL, median (IQR)	1.63 (0.68-3.47)	1.71 (0.72-3.52)	1.48 (0.61-3.31)	0.243
Severe acute pancreatitis	98 (40.0)	71 (41.3)	27 (37.0)	0.527

Data are presented as n (%). IQR: Interquartile range; SD: Standard deviation.

Table 2 Association of combined intra-abdominal pressure-procalcitonin risk stratification with major clinical outcomes

Clinical outcomes	Low risk (n = 98)	Moderate-low risk (n = 82)	Moderate-high risk (n = 46)	High risk (n = 19)	P value
Severe AP	13 (13.3)	31 (37.8)	36 (78.3)	18 (94.7)	< 0.001
28-day all-cause mortality	4 (4.1)	9 (11.0)	9 (19.6)	7 (36.8)	< 0.001
180-day mortality	6 (6.1)	12 (14.6)	11 (23.9)	8 (42.1)	< 0.001
MODS	8 (8.2)	21 (25.6)	24 (52.2)	15 (78.9)	< 0.001
Abdominal compartment syndrome	2 (2.0)	7 (8.5)	11 (23.9)	11 (57.9)	< 0.001
ICU admission	11 (11.2)	31 (37.8)	33 (71.7)	18 (94.7)	< 0.001
ICU LOS (days), mean ± SD	2.2 ± 1.6	6.7 ± 3.9	9.9 ± 5.4	16.3 ± 8.7	< 0.001
Mechanical ventilation	3 (3.1)	11 (13.4)	17 (37.0)	13 (68.4)	< 0.001
Mechanical ventilation duration (days), mean ± SD	1.7 ± 0.9	3.8 ± 2.3	6.9 ± 3.9	10.8 ± 5.7	< 0.001
Infectious complications	7 (7.1)	17 (20.7)	20 (43.5)	13 (68.4)	< 0.001
Hospital LOS (days), mean ± SD	9.7 ± 3.6	16.3 ± 6.2	23.5 ± 9.4	29.7 ± 13.2	< 0.001
Total cost (× 10000 RMB), mean ± SD	3.9 ± 1.9	8.1 ± 3.5	14.9 ± 6.7	23.8 ± 11.3	< 0.001
Stratified by etiology
Hypertriglyceridemic AP patients (n = 53)
28-day mortality	1/12 (8.3)	3/17 (17.6)	4/15 (26.7)	4/9 (44.4)	0.038
MODS	2/12 (16.7)	7/17 (41.2)	10/15 (66.7)	8/9 (88.9)	0.003
Biliary AP (n = 123)
28-day mortality	2/53 (3.8)	4/39 (10.3)	3/21 (14.3)	2/10 (20.0)	0.014
MODS	4/53 (7.5)	11/39 (28.2)	9/21 (42.9)	6/10 (60.0)	< 0.001
Alcoholic AP (n = 46)
28-day mortality	1/21 (4.8)	2/16 (12.5)	2/7 (28.6)	1/2 (50.0)	0.113
MODS	2/21 (9.5)	5/16 (31.3)	3/7 (42.9)	1/2 (50.0)	0.046

Data are presented as n (%). Risk stratification was based on intra-abdominal pressure ≥ 10.5 mmHg and procalcitonin ≥ 0.92 ng/mL cutoffs from the training set. AP: Acute pancreatitis; ICU: Intensive care unit; LOS: Length of stay; MODS: Multiple organ dysfunction syndrome; SD: Standard deviation.

Table 3 Performance comparison of different models for predicting 28-day mortality

Prediction models	Area under the curve (95%CI)	Sensitivity (%)	Specificity (%)	Positive predictive value (%)	Negative predictive value (%)	P value
IAP model alone	0.772 (0.686-0.858)	71.7	73.8	47.3	88.9	0.008a
PCT model alone	0.765 (0.679-0.851)	68.9	72.6	46.1	87.3	0.005a
Acute Physiology and Chronic Health Evaluation II score	0.796 (0.718-0.874)	75.1	70.3	46.8	89.1	0.041a
Logistic regression IAP-PCT model	0.813 (0.738-0.888)	76.8	74.2	50.3	90.3	0.087
ML-IAP-PCT model	0.837 (0.765-0.909)	78.6	76.5	53.1	91.4	Reference
ML-comprehensive model1	0.842 (0.772-0.912)	79.3	77.2	54.5	91.7	0.386

¹Machine learning-comprehensive model included intra-abdominal pressure, procalcitonin, and nine clinical variables.

^aP < 0.05 vs the machine learning-intra-abdominal pressure-procalcitonin model according to the DeLong test.

IAP: Intra-abdominal pressure; ML: Machine learning; PCT: Procalcitonin; CI: Confidence interval.

Table 4 Efficacy of precision intervention based on propensity score matching

Outcome measures	Intervention group (n = 76)	Conventional group (n = 76)	Relative risk/mean difference (95%CI)	P value
Primary outcomes
28-day all-cause mortality	12 (15.8)	19 (25.0)	0.63 (0.33-0.98)	0.043
180-day mortality	15 (19.7)	23 (30.3)	0.65 (0.37-0.92)	0.038
Secondary outcomes
MODS	37 (48.7)	47 (61.8)	0.79 (0.58-0.96)	0.027
Abdominal compartment syndrome	16 (21.1)	27 (35.5)	0.59 (0.35-0.87)	0.011
ICU admission	44 (57.9)	51 (67.1)	0.86 (0.67-1.03)	0.172
ICU LOS (days), mean ± SD	7.8 ± 4.5	10.3 ± 5.8	-2.5 (-4.1 to -0.9)	0.029
Mechanical ventilation	19 (25.0)	27 (35.5)	0.70 (0.43-1.05)	0.078
Mechanical ventilation duration (days), mean ± SD	4.6 ± 3.1	6.9 ± 4.0	-2.3 (-3.4 to -1.2)	0.003
Infectious complications	24 (31.6)	32 (42.1)	0.75 (0.49-0.98)	0.047
Hospital LOS (days), mean ± SD	18.4 ± 8.6	22.7 ± 10.1	-4.3 (-7.1 to -1.5)	0.036
Total cost (× 10000 RMB), mean ± SD	10.3 ± 5.6	13.8 ± 7.3	-3.5 (-5.6 to -1.4)	0.021
Subgroup analysis
Hypertriglyceridemic AP subgroup (n = 28 pairs)
MODS	11 (39.3)	17 (60.7)	0.65 (0.38-0.94)	0.018
28-day mortality	4 (14.3)	8 (28.6)	0.50 (0.22-0.99)	0.041
Biliary AP subgroup (n = 40 pairs)
MODS	21 (52.5)	28 (70.0)	0.75 (0.52-0.98)	0.032
28-day mortality	7 (17.5)	10 (25.0)	0.70 (0.37-1.33)	0.263
Alcoholic AP subgroup (n = 16 pairs)
MODS	9 (56.3)	11 (68.8)	0.82 (0.47-1.43)	0.465
28-day mortality	3 (18.8)	4 (25.0)	0.75 (0.21-2.65)	0.659
Adjusted analysis
28-day mortality, adjusted OR1	-	-	0.59 (0.29-0.97)	0.038
MODS, adjusted OR1	-	-	0.71 (0.41-0.93)	0.023

¹Adjusted for age, sex, etiology, Acute Physiology and Chronic Health Evaluation II score, baseline intra-abdominal pressure, procalcitonin, and comorbidities.

Data are presented as n (%). Propensity score matching included age, sex, etiology, Acute Physiology and Chronic Health Evaluation II score, body mass index, baseline laboratory values, and admission time. AP: Acute pancreatitis; ICU: Intensive care unit; LOS: Length of stay; MODS: Multiple organ dysfunction syndrome; OR: Odds ratio; CI: Confidence interval; SD: Standard deviation.