Baseline description of the study population
Population characteristics based on the quartile distribution of SA are presented in Table 1. A total of 11,362 participants were included in this study, with an average age of 51.96, 49.63% men and 50.37% women. Periodontitis was found in 39.03% of the subjects. The mean and standard deviation of SA was 4.26 ± 0.34. Subjects in the highest SA group had a lower prevalence of periodontitis (Q1 43.70%, Q2 43.86%, Q3 38.47%, Q4 31.52%; P < 0.001). In addition, subjects in the highest SA group were more likely to be male, non-Hispanic White, college-educated, married or living with a partner, have a body mass index close to the normal range, a higher poverty-to-income ratio, have hypertension, not be hypercholesterolemic, and consume alcohol.
Table 1
Baseline Participant Characteristics(N = 11,362)
SA, g/dl quartile | Total(N = 11,362) | Q1(n = 2810) | Q2(n = 2581) | Q3(n = 2779) | Q4(n = 3192) | P-value |
Age(year, mean ± SD) | 51.96 ± 15.15 | 53.0 ± 15.90 | 54.7 ± 14.83 | 52.53 ± 14.50 | 48.2 ± 14.58 | < 0.001 |
Sex,n(%) | | | | | | < 0.001 |
Male | 5639 (49.63%) | 850 (30.25%) | 1164 (45.10%) | 1516 (54.55%) | 2109 (66.07%) |
Female | 5723 (50.37%) | 1960 (69.75%) | 1417 (54.90%) | 1263 (45.45%) | 1083 (33.93%) |
Race/Ethnicity,n(%) | | | | | | < 0.001 |
Non–Hispanic white | 5561 (48.94%) | 1192 (42.42%) | 1248 (48.35%) | 1395 (50.20%) | 1726 (54.07%) |
Non–Hispanic black | 2159 (19.00%) | 814 (28.97%) | 545 (21.12%) | 435 (15.65%) | 365 (11.43%) |
Mexican American | 1720 (15.14%) | 403 (14.34%) | 368 (14.26%) | 431 (15.51%) | 518 (16.23%) |
Other Race/Ethnicity | 1922 (16.92%) | 401 (14.27%) | 420 (16.27%) | 518 (18.64%) | 583 (18.26%) |
Education Level,n(%) | | | | | | < 0.001 |
Below high school | 2454 (21.60%) | 679 (24.16%) | 560 (21.70%) | 587 (21.12%) | 628 (19.67%) |
High school | 2468 (21.72%) | 644 (22.92%) | 553 (21.43%) | 603 (21.70%) | 668 (20.93%) |
College or above | 6440 (56.68%) | 1487 (52.92%) | 1468 (56.88%) | 1589 (57.18%) | 1896 (59.40%) |
Marital Status,n(%) | | | | | | < 0.001 |
Never married | 1294 (11.39%) | 347 (12.35%) | 274 (10.62%) | 273 (9.82%) | 400 (12.53%) |
Married/Living with partner | 7505 (66.05%) | 1656 (58.93%) | 1680 (65.09%) | 1909 (68.69%) | 2260 (70.80%) |
Widowed/Divorced/Separated | 2563 (22.56%) | 807 (28.72%) | 627 (24.29%) | 597 (21.48%) | 532 (16.67%) |
PIR,n(%) | | | | | | < 0.001 |
<1 | 1870 (16.46%) | 566 (20.14%) | 439 (17.01%) | 418 (15.04%) | 447 (14.00%) |
[1, 3) | 4405 (38.77%) | 1211 (43.10%) | 1020 (39.52%) | 1054 (37.93%) | 1120 (35.09%) |
≥ 3 | 5087 (44.77%) | 1033 (36.76%) | 1122 (43.47%) | 1307 (47.03%) | 1625 (50.91%) |
Alcohol Drinkers,n(%) | | | | | | < 0.001 |
Non-drinkers | 1484 (13.06%) | 473 (16.83%) | 358 (13.87%) | 339 (12.20%) | 314 (9.84%) |
Moderate alcohol use | 5361 (47.18%) | 1336 (47.54%) | 1277 (49.48%) | 1294 (46.56%) | 1454 (45.55%) |
Heavy alcohol use | 4517 (39.76%) | 1001 (35.62%) | 946 (36.65%) | 1146 (41.24%) | 1424 (44.61%) |
BMI,n(%) | | | | | | < 0.001 |
normal | 3025 (26.62%) | 497 (17.69%) | 606 (23.48%) | 773 (27.82%) | 1149 (36.00%) |
overweight | 3993 (35.14%) | 761 (27.08%) | 885 (34.29%) | 1090 (39.22%) | 1257 (39.38%) |
Obesity | 3554 (31.28%) | 1114 (39.64%) | 913 (35.37%) | 793 (28.54%) | 734 (22.99%) |
morbid obesity | 790 (6.95%) | 438 (15.59%) | 177 (6.86%) | 123 (4.43%) | 52 (1.63%) |
HBP,n(%) | | | | | | < 0.001 |
No | 4746 (41.77%) | 1092 (38.86%) | 1014 (39.29%) | 1179 (42.43%) | 1461 (45.77%) |
Yes | 6616 (58.23%) | 1718 (61.14%) | 1567 (60.71%) | 1600 (57.57%) | 1731 (54.23%) |
Diabetes,n(%) | | | | | | < 0.001 |
No | 591 (5.20%) | 156 (5.55%) | 155 (6.01%) | 161 (5.79%) | 119 (3.73%) |
Yes | 1447 (12.74%) | 517 (18.40%) | 361 (13.99%) | 303 (10.90%) | 266 (8.33%) |
Hypercholesterolemia,n (%) | | | | | | 0.003 |
no | 5875 (51.71%) | 1522 (54.16%) | 1358 (52.62%) | 1377 (49.55%) | 1618 (50.69%) |
yes | 5487 (48.29%) | 1288 (45.84%) | 1223 (47.38%) | 1402 (50.45%) | 1574 (49.31%) |
Periodontitis,n (%) | | | | | | < 0.001 |
no | 6927 (60.97%) | 1582 (56.30%) | 1449 (56.14%) | 1710 (61.53%) | 2186 (68.48%) |
yes | 4435 (39.03%) | 1228 (43.70%) | 1132 (43.86%) | 1069 (38.47%) | 1006 (31.52%) |
Smokers,n (%) | | | | | | 0.138 |
Never smoker | 6273 (55.21%) | 1583 (56.33%) | 1428 (55.33%) | 1555 (55.96%) | 1707 (53.48%) |
Former smoker | 3057 (26.91%) | 710 (25.27%) | 691 (26.77%) | 751 (27.02%) | 905 (28.35%) |
Current smoker | 2032 (17.88%) | 517 (18.40%) | 462 (17.90%) | 473 (17.02%) | 580 (18.17%) |
Numbers that do not add up to 100% are attributable to missing data. |
The association between SA and periodontitis
Based on the three-group logistic regression model, the association between SA and periodontitis is presented in Table 2. The initial analysis of SA was conducted as a continuous variable. The results indicated a negative correlation between SA and periodontitis in the crude model (OR = 0.61, 95% CI 0.55, 0.68, P < 0.0001). After adjusting for some of the covariates, similar results were still observed in Model I (OR = 0.55,95%CI 0.48, 0.62, P < 0.0001). After adjusting for all covariates in Model II, consistent results were observed, with a 35% reduction in the risk of periodontitis for each 1.0 g/dl increase in SA concentration (OR = 0.65,95% CI 0.57, 0.75, P < 0.0001). When SA was analyzed as quartiles, in Model II, the risk of periodontitis was significantly lower in quartiles Q3 (OR = 0.82,95%CI 0.73, 0.93, P = 0.0021), and Q4 (OR = 0.67,95%CI 0.59, 0.76, P < 0.0001) groups compared to the lowest quartile(Q1). The observed effect value in Q2 (OR = 0.98, 95% CI 0.87, 1.11, P = 0.7757) did not reach statistical significance. Subsequent Smooth curve fitting revealed a non-linear relationship between SA and periodontitis (Fig. 3). Threshold effect analysis(Table 3) suggested that while the increase in SA concentration was associated with a trend toward increased risk of periodontitis before the turning point, this trend was not statistically significant (OR = 1.55, 95% CI 1.00, 2.41, P = 0.050). However, the risk of developing periodontitis decreased once the SA concentration reached 3.9 g/dl (OR = 0.52, 95% CI 0.43, 0.62, P < 0.001). These findings indicate that the risk of periodontitis decreases with increasing SA concentration, particularly after it surpasses 3.9 g/dl. Additionally, there was a notable 48% reduction in the risk of periodontitis for every 1.0 g/dl increase in SA concentration.
Table 2
Association of SA with periodontitis.
Exposure | Crude Model OR(95%CI)p-value | Model I OR(95%CI)p-value | Model II OR(95%CI)p-value |
Serum Albumin, g/dl | 0.61(0.55,0.68) < 0.001 | 0.55(0.48,0.62) < 0.001 | 0.65(0.57,0.75) < 0.001 |
Serum Albumin(quartile) | | | |
Q1 | reference | reference | reference |
Q2 | 1.01 (0.90, 1.12) 0.907 | 0.88 (0.78, 0.99) 0.034 | 0.98 (0.87, 1.11) 0.776 |
Q3 | 0.81(0.72,0.90) < 0.001 | 0.70(0.63,0.79) < 0.001 | 0.82 (0.73, 0.93) < 0.001 |
Q4 | 0.59(0.53,0.66) < 0.001 | 0.56(0.49,0.63) < 0.001 | 0.67(0.59,0.76) < 0.001 |
P for trend | < 0.001 | < 0.001 | < 0.001 |
OR, odds ratio; CI, confidence intervals. |
Table 3
Threshold effect analysis of SA and periodontitis using piece-wise logistic regression.
Serum albumin, g/dl | Periodontitis (OR, 95%CI, P) |
Fitting by weighted logistic regression model | 0.65 (0.57, 0.75) < 0.001 |
Fitting by weighted two-piecewise linear logistic mode | |
Inflection point | 3.9 |
<3.9 | 1.55 (1.00, 2.41) 0.050 |
≥3.9 | 0.52 (0.43, 0.62) < 0.001 |
Log likelihood ratio test | < 0.001 |
Periodontitis contained mild, moderate, and severe periodontitis. |
Subgroup Analysis
To delve deeper into potential covariates influencing the relationship between SA and periodontitis, subgroup analyses were conducted(Table 4). The findings revealed a persistent negative correlation between SA levels and periodontitis. Intriguingly, this correlation varied by gender. Specifically, the impact of SA on periodontitis was notably more pronounced in males (OR = 0.51, 95% CI 0.41, 0.63, P < 0.0001) compared to females (OR = 0.79, 95% CI 0.64, 0.96, P = 0.0184). Further analysis(Table 5) of the associations between SA and periodontitis by gender revealed that in Model II, the negative correlation between SA and periodontitis persisted in females (OR = 0.79, 95% CI 0.64, 0.96, P = 0.0184), while in males, this association was even more robust (OR = 0.51, 95% CI 0.41, 0.63, P < 0.0001).
Table 4
Subgroup analysis for the association between LE8 and periodontitis.
Subgroup | N | Periodontitis [OR (95% CI)] | P for interaction |
Sex | | | 0.007 |
male | 5639 | 0.51 (0.41, 0.63) < 0.001 | |
female | 5723 | 0.79 (0.64, 0.96) 0.018 | |
Agegroup | | | 0.142 |
<44 | 3841 | 0.76 (0.59, 0.98) 0.033 | |
[44,60) | 3645 | 0.50 (0.38, 0.64) < 0.001 | |
≥ 60 | 3876 | 0.63 (0.50, 0.80) < 0.001 | |
Race | | | 0.505 |
Non–hispanic White | 5561 | 0.69 (0.55, 0.85) < 0.001 | |
Non–hispanic Black | 2159 | 0.63 (0.46, 0.87) 0.005 | |
Mexican American | 1720 | 0.52 (0.38, 0.72) < 0.001 | |
Other Race/ethnicity | 1922 | 0.78 (0.55, 1.10) 0.161 | |
Marital status | | | 0.900 |
Never married | 1294 | 0.68 (0.44, 1.04) 0.072 | |
Married/living with partner | 7505 | 0.68 (0.57, 0.81) < 0.001 | |
Widowed/divorced/Separated | 2563 | 0.60 (0.45, 0.81) < 0.001 | |
Education level | | | 0.422 |
below high school | 2454 | 0.59 (0.45, 0.77) < 0.001 | |
High school | 2468 | 0.59 (0.44, 0.79) < 0.001 | |
College or above | 6440 | 0.74 (0.60, 0.91) 0.004 | |
PIR | | | 0.056 |
< 1 | 1870 | 0.61 (0.45, 0.84) 0.002 | |
[1, 3) | 4405 | 0.57 (0.46, 0.71) < 0.001 | |
≥ 3 | 5087 | 0.81 (0.64, 1.03) 0.090 | |
BMI | | | 0.957 |
normal | 3025 | 0.71 (0.53, 0.94) 0.018 | |
overweight | 3993 | 0.66 (0.52, 0.83) < 0.001 | |
Obesity | 3554 | 0.63 (0.49, 0.80) < 0.001 | |
morbid obesity | 790 | 0.62 (0.36, 1.06) 0.082 | |
HBP | | | 0.292 |
no | 4746 | 0.79 (0.63, 1.00) 0.049 | |
yes | 6616 | 0.58 (0.48, 0.70) < 0.001 | |
Diabetes | | | 0.806 |
no | 591 | 0.65 (0.33, 1.29) 0.219 | |
yes | 1447 | 0.55 (0.38, 0.78) < 0.001 | |
Hypercholesterolemia | | | 0.877 |
no | 5875 | 0.65 (0.53, 0.80) < 0.001 | |
yes | 5487 | 0.66 (0.54, 0.80) < 0.001 | |
Smoking | | | 0.736 |
Never smoker | 6273 | 0.72 (0.59, 0.88) 0.001 | |
Former smoker | 3057 | 0.62 (0.47, 0.80) < 0.001 | |
Current smoker | 2032 | 0.60 (0.43, 0.84) 0.003 | |
Numbers that do not add up to 100% are attributable to missing data. |
Table 5
Association between SA and periodontitis stratified by gender.
| Crude Model | Model I | Model II |
Male | | | |
Serum albumin | 0.24 (0.20, 0.28) < 0.001 | 0.40 (0.33, 0.49) < 0.001 | 0.51 (0.41, 0.63) < 0.001 |
Serum albumin(quartile) | | | |
Q1 | reference | reference | reference |
Q2 | 0.65 (0.54, 0.78) < 0.001 | 0.74 (0.61, 0.89) 0.002 | 0.86 (0.71, 1.05) 0.141 |
Q3 | 0.49 (0.41, 0.58) < 0.001 | 0.62 (0.52, 0.74) < 0.001 | 0.77 (0.63, 0.93) 0.007 |
Q4 | 0.31 (0.26, 0.36) < 0.001 | 0.46 (0.39, 0.55) < 0.001 | 0.58 (0.48, 0.70) < 0.001 |
Female | | | |
Serum albumin | 0.70 (0.59, 0.82) < 0.001 | 0.66 (0.55, 0.79) < 0.001 | 0.79 (0.64, 0.96) 0.018 |
Serum albumin(quartile) | | | |
Q1 | reference | reference | reference |
Q2 | 1.04 (0.90, 1.20) 0.621 | 0.97 (0.83, 1.13) 0.663 | 1.06 (0.90, 1.24) 0.476 |
Q3 | 0.74 (0.64, 0.87) < 0.001 | 0.72 (0.62, 0.85) < 0.001 | 0.82 (0.69, 0.97) 0.022 |
Q4 | 0.58 (0.49, 0.68) < 0.001 | 0.62 (0.52, 0.75) < 0.001 | 0.75 (0.61, 0.91) 0.003 |
The model was not adjusted for the stratification variable itself in the subgroup analysis by gender. |