The influence of seasonal factors on the incidence of peritoneal dialysis-associated peritonitis

Figures & data

Table 1. Characteristics of all PD patients with peritonitis during the study period, from 2011 to 2019.

Characteristics	Spring (n = 160)	Summer (n = 186)	Autumn (n = 167)	Winter (n = 154)	p-Value
Age (years)	63.13 ± 16.57	61.38 ± 17.11	63.99 ± 14.78	58.87 ± 16.32	0.253
Male (n, %)	72 (45.0)	92(49.5)	74 (44.3)	78 (50.6)	0.759
PD duration (months)	38.13 ± 26.54	42.62 ± 19.11	39.83 ± 24.91	30.79 ± 24.65	0.372
BMI (kg/m^2)	22.41 ± 3.20	23.26 ± 3.51	22.73 ± 2.84	22.63 ± 3.56	0.878
Potassium (mmol/L)	3.73 ± 0.67	3.67 ± 0.91	3.64 ± 0.66	3.56 ± 0.57	0.275
Hemoglobin (g/L)	107.77 ± 24.18	109.20 ± 23.61	108.13 ± 21.95	109.43 ± 18.34	0.246
Albumin (g/L)	32.12 ± 5.21	31.78 ± 6.34	32.10 ± 5.72	34.14 ± 4.79	0.384
Phosphorus (mmol/L)	1.40 ± 0.52	1.43 ± 0.54	1.47 ± 0.49	1.46 ± 0.44	0.193
Total KT/Vurea	1.68 ± 0.37	1.69 ± 0.48	1.76 ± 0.41	1.81 ± 0.40	0.103
Total weekly Ccr ml/min/1.73 m^2	53.21 ± 15.19	52.18 ± 18.10	53.29 ± 14.78	56.82 ± 16.96	0.590

BMI: Body mass index; KT/Vurea: dialysis clearance of urea; Ccr: creatinine clearance rate.

Table 2. Comparisons of the clinical manifestations and predisposing factors for patients during different seasons.

Outcome	Spring (n = 160)	Summer (n = 186)	Autumn (n = 167)	Winter (n = 154)	p-Value
Clinical manifestations [n (%)]
Fever	47 (29.4)	73 (39.2)	65 (38.9)	51 (33.1)	0.172
Abdominal pain	142 (88.8)	160 (86.0)	146 (87.4)	123 (79.9)	0.118
Diarrhea	40 (25.0)	66 (35.5)	38 (22.8)	42 (27.3)	0.042
The amount of ultrafiltration decreased	105 (65.6)	117 (62.9))	130 (70.7)	101 (65.6)	0.488
Muddy dialysate	137 (85.6)	164 (88.2)	144 (86.2)	126 (81.8)	0.417
Cause [n (%)]
Operation	53 (33.1)	59 (31.7)	64 (38.3)	42 (27.3)	0.207
Eating raw and cold food	48 (30.0)	63 (33.9)	37 (22.2)	40 (26.0)	0.086
Constipation	15 (9.4)	27 (11.3)	17 (10.2)	24 (15.6)	0.319
Systemic infection	16 (10.0)	15 (8.1)	18 (10.8)	22 (14.3)	0.318
Exit-site infection	13 (8.1)	13 (7.0)	16 (9.6)	12 (7.8)	0.845
Malnutrition	6 (3.8)	5 (2.7)	7 (4.2)	9 (5.8)	0.530
Other	9 (5.6)	4 ( 2.2)	8 (4.8)	5 (3.2)	0.455

Figure 1. Changes in the peritonitis rate at the Second Affiliated Hospital of Suzhou University, from 2011 to 2019.

Table 3. Overall peritonitis rate for different seasons (episodes/patient-year).

Year	Spring	Summer	Autumn	Winter
2011	0.15	0.28	0.23	0.24
2012	0.27	0.25	0.20	0.25
2013	0.25	0.30	0.26	0.23
2014	0.14	0.29	0.25	0.25
2015	0.28	0.25	0.21	0.18
2016	0.21	0.22	0.25	0.15
2017	0.25	0.26	0.19	0.17
2018	0.14	0.24	0.20	0.18
2019	0.18	0.26	0.21	0.12

Figure 2. The incidence of peritonitis and varying temperatures during different seasons, from 2011 to 2019.

Figure 3. Incidence of peritonitis and humidity changes during different seasons, from 2011 to 2019.

Table 4. Microbiologic causes of peritonitis.

Organisms identified	Case [n (%)]
Gram-positive organisms	326 (49.54)
Coagulase-negative Staphylococci	137 (20.82)
Streptococci	104 (15.81)
Enterococcus	26 (3.96)
Staphylococcus aureus	21 (3.19)
Gram-negative organisms	182 (27.66)
Enterobacterial	208 (31.61)
Escherichia coli	76 (11.55)
K. pneumoniae	35 (5.32)
Fungus	20 (3.04)
Culture-negative	92 (13.98)
Others	38 (5.78)
Total	658

Table 5. Relationships between microorganisms and seasonal variations.

Organisms identified	Spring	summer	Autumn	Winter	p-Value
Gram-positive organisms	0.108	0.093	0.088	0.117	0.626
	(0.079–0.137)	(0.070–0.117)	(0.066–0.111)	(0.094–0.140)
Coagulase-negative Staphylococci	0.054	0.058	0.042	0.053	0.292
	(0.032–0.075)	(0.042–0.074)	(0.029–0.055)	(0.038–0.068)
Streptococci	0.047	0.023	0.030	0.038	0.453
	(0.031–0.062)	(0.014–0.031)	(0.018–0.043)	(0.026–0.050)
Staphylococcus aureus	0.003	0.011	0.006	0.007	0.220
	(0.001–0.006)	(0.004–0.018)	(0.001–0.012)	(0.001–0.014)
Gram-negative organisms	0.048	0.091	0.056	0.043	0.050
	(0.030–0.066)	(0.069–0.113)	(0.041–0.071))	(0.029–0.058)
Enterobacterial	0.052	0.095	0.061	0.050	0.113
	(0.035–0.070)	(0.074–0.117)	(0.043–0.078)	(0.033–0.068)
Culture-negative	0.029	0.033	0.042	0.032	0.570
	(0.016–0.042)	(0.020–0.047)	(0.026–0.058)	(0.019–0.044)
Fungus	0.005	0.006	0.010	0.006	0.747
	(0.000–0.009)	(0.000–0.012)	(0.001–0.019)	(0.001–0.013)

Figure 4. Relationships between the gram-negative bacterial peritonitis rate and average temperature and average humidity.

Figure 5. Relationships between the enterobacterial peritonitis rate and the average temperature and average humidity.

Table 6. Logistic univariate regression analysis for peritonitis.

Variable	B value	OR value	95% CI	p-Value
Age	1.245	3.472	1.687–8.587	0.000
Gender	−0.212	0.809	0.654–1.002	0.052
Diabetes mellitus	0.405	1.499	0.587–3.833	0.397
Hemoglobin (g/L)	−0.012	0.988	0.635–0.981	0.022
Albumin (g/L)	−0.751	0.472	0.851–0.996	0.007
Serum creatinine	−0.213	0.808	0.430–1.517	0.507
Cholesterol	0.428	1.534	0.92–1.409	0.327
Potassium (mmol/L)	0.574	1.775	0.667–3.517	0.411
hs-CRP(Log10) (mg/L)	1.685	5.392	3.673–7.917	0.000
Seasonal grouping
Winter	Reference	Reference	Reference	Reference
Spring	0.604	1.830	0.706–4.744	0.214
Summer	0.934	2.545	1.430–4.528	0.041
Autumn	0.695	2.003	0.806–2.942	0.109

Table 7. Logistic multivariate regression analysis for peritonitis.

Variable	B value	OR value	95% CI	p-Value
Age	0.307	1.360	1.005–1.837	0.012
Gender	−0.019	0.981	0.958–1.006	0.134
Hemoglobin (g/L)	−0.022	0.978	0.945–1.013	0.220
Albumin (g/L)	−0.577	0.561	0.483–0.925	0.034
hs-CRP(Log10) (mg/L)	0.721	2.056	1.202–3.591	0.002
Seasonal grouping
Winter	Reference	Reference	Reference	Reference
Spring	0.048	1.049	0.975–3.130	0.401
Summer	0.307	1.359	0.985–4.637	0.246
Autumn	0.026	1.026	0.603–3.899	0.383

Table 8. Clinical outcomes of peritonitis, according to the four seasons [(Case ％)].

Outcome	Spring	Summer	Autumn	Winter	p-Value
Cure	147 (91.8%)	152 (81.7%)	148 (88.6%)	135 (87.7%)	0.037
failure	13 (8.2%)	34 (18.3%)	19 (11.4%)	19 (12.3%)
hemodialysis	9 (5.6%)	23 (12.4%)	11 (6.6%)	9 (5.8%)
death	4 (2.6%)	11 (5.9%)	8 (4.8%)	10 (6.5%)