Elevated levels of fructosamine are independently associated with SARS-CoV-2 reinfection: A 12-mo follow-up study

Table 1 Baseline characteristics of the study cohort

Variable	Total	Elevated FMN1	Nonelevated FMN2	P value
Patients, n (%)	146	47 (68)	99 (32)
Gender, n (%)				0.319
Male	72 (49)	26 (36)	46 (64)
Female	74 (51)	21 (28)	53 (72)
Age (yr)	49 (39-55)	53 (43-58)	47 (35-53)	0.008
Diabetes mellitus, n (%)	17 (12)	14 (82)	3 (18)	0.000
Hypertension, n (%)	18 (12)	8 (44)	10 (56)	0.023
Respiratory failure, n (%)	12 (8)	6 (50)	6 (50)	0.291
Corticosteroid therapy, n (%)	30 (21)	5 (17)	25 (83)	0.041
WBC [(4.0 × 109/L)-(10.0 × 109/L)]	4.64 (3.63-5.82)	5.06 (3.85-6.45)	4.58 (3.45-5.40)	0.067
CRP (< 5 mg/L)	7.30 (5.0-25.60)	6.80 (5.0-34.90)	7.80 (5.0-23.60)	0.320
PNI	47.80 (44.26-50.58)	49.55 (46.05-50.95)	47.05 (44.05-49.55)	0.061
ALT (0-55 U/L)	20.50 (14.0-29.0)	22.00 (15.0-31.0)	19.00 (13.0-28.0)	0.138
AST (0-55 U/L)	23.00 (18.0-31.0)	25.00 (19.0-32.0)	22.00 (18.0-30.0)	0.016
SCR (45-84 μmol/L)	62 (50-74)	64 (55-73)	61 (50-75)	0.460
TC (3.60-5.70 mmol/L)	4.24 ± 0.77	4.11 ± 0.79	4.30 ± 0.76	0.176
TG (0.60-1.70 mmol/L)	1.16 (0.86-1.69)	1.22 (0.88-1.77)	1.14 (0.86-1.66)	0.239
HDL-C (1.09-2.27 mmol/L)	0.95 (0.80-1.16)	0.92 (0.76-1.16)	0.98 (0.83-1.16)	0.314
LDL-C (1.30-3.37 mmol/L)	2.30 (1.94-2.91)	2.22 (1.90-2.78)	2.32 (1.98-2.92)	0.242
Reinfection case, n (%)	11 (7.5)	8 (73)	3 (17)	0.008

¹Upper third of fructosamine levels.

²Lower two-thirds of fructosamine levels.

Data are presented as the mean (SD) for normally distributed data and median (interquartile range) for non-normal distributed data. PNI = serum albumin (g/L) + 5 × lymphocyte count (× 10⁹/L). P value was calculated using one-sample Kolmogorov-Smirnov test or t-test. WBC: White blood cell count; FMN: Fructosamine; CRP: C-reactive protein; PNI: Prognostic nutritional index; ALT: Alanine aminotransferase; AST: Aspartate aminotransferase; SCR: Serum creatinine; TG: Triglyceride; TC: Total cholesterol; HDL-C: High-density lipoprotein cholesterol; LDL-C: Low-density lipoprotein cholesterol.

Table 2 Association of fructosamine levels with SARS-CoV-2 reinfection

FMN dichotomy	B	SE	HR	95%CI	P value
Model 1	1.827	0.677	6.214	1.647-23.438	0.007
Model 2	1.898	0.759	6.674	1.507-29.544	0.012
Model 3	1.832	0.772	6.249	1.377-28.351	0.018

Model 1: Unadjusted. Model 2: Adjusted for age, gender, diabetes mellitus, corticosteroid therapy, and hypertension. Model 3: Adjusted for Model 2 and acute liver failure, acute kidney failure, white blood cell count, C-reactive protein, prognostic nutritional index, and blood lipids. P value for hazard ratio with 95% confidence interval was calculated using Cox regression models to indicate a significant association. FMN: Fructosamine; HR: Hazard ratio; CI: Confidence interval.