Table 3.
Covariate-adjusted estimates of ANA associations with selected characteristics by time period. a
| ANA Prevalence Odds Ratio (95% CI) for Characteristic Category | ||||
|---|---|---|---|---|
| Characteristic b | Period 1: 1988-1991 | Period 2: 1999-2004 | Period 3: 2011-2012 | |
| Sex | ||||
| Male | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Female | 2.53 (1.90 - 3.36) | 2.97 (2.30 - 3.84) | 1.94 (1.57 - 2.40) | |
| P: | < 0.0001 | < 0.0001 | < 0.0001 | |
| Age (years) | ||||
| Adolescent (12-19) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Younger Adult (20-49) | 2.27 (1.43 - 3.62) | 0.97 (0.66 - 1.42) | 1.00 (0.73 - 1.38) | |
| Older Adult ( ≥ 50 ) | 3.63 (2.02 - 6.55) | 1.80 (1.23 - 2.63) | 1.71 (1.21 - 2.42) | |
| P: | 0.0007 | 0.002 | 0.0009 | |
| Race/Ethnicity | ||||
| Non-Hispanic White | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Non-Hispanic Black | 1.75 (1.33 - 2.31) | 1.47 (1.13 - 1.92) | 1.20 (0.95 - 1.51) | |
| Mexican-American | 1.87 (1.40 - 2.50) | 1.34 (1.01 - 1.76) | 0.87 (0.63 - 1.19) | |
| Other | 1.39 (0.62 - 3.13) | 0.90 (0.60 - 1.35) | 0.90 (0.70 - 1.15) | |
| P: | 0.0007 | 0.03 | 0.18 | |
| Body Mass Index (BMI) | ||||
| Underweight/Healthy | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Overweight | 0.74 (0.54 - 1.02) | 0.83 (0.62 - 1.11) | 1.20 (0.96 - 1.49) | |
| Obese | 0.90 (0.65 - 1.25) | 1.00 (0.79 - 1.27) | 1.13 (0.88 - 1.46) | |
| P: | 0.19 | 0.39 | 0.10 | |
| Smoking Exposure | ||||
| None | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Second-Hand | 0.68 (0.44 - 1.05) | 1.14 (0.87 - 1.50) | 1.02 (0.79 - 1.32) | |
| Active | 0.56 (0.31 - 1.01) | 0.70 (0.50 - 0.97) | 0.83 (0.55 - 1.23) | |
| P: | 0.13 | 0.07 | 0.54 | |
| Alcohol Consumption | ||||
| None | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | |
| Light | 1.07 (0.70 - 1.63) | 0.96 (0.66 - 1.40) | 0.90 (0.65 - 1.25) | |
| Moderate/Heavy | 0.56 (0.34 - 0.92) | 0.64 (0.44 - 0.94) | 0.91 (0.62 - 1.34) | |
| P: | 0.03 | 0.06 | 0.80 | |
Abbreviations: ANA = antinuclear antibodies; CI = confidence interval.
The ANA association with each characteristic category was assessed by estimating a period-specific odds ratio under a logistic regression model that adjusted for the survey design variables (strata, clusters, and sampling weights) and categorical covariates for sex, age, race/ethnicity, and the characteristic of interest. The P value for assessing a characteristic’s overall association with ANA in a given time period was based on an F-test from a statistical contrast.
BMI was categorized as underweight/healthy, overweight, or obese using standard cut points of <25, 25 to <30, or ≥30 kg/m2 for persons ≥20 years old and by applying 2000 CDC growth chart percentiles of <85, 85 to <95, or ≥95 for persons 12-19 years old. Smoking exposure was based on current measured cotinine levels and classified as none (<0.05 ng/ml), second-hand (0.05 to 15 ng/ml), or active (>15 ng/ml). Alcohol consumption (available for ages ≥20 years) was based on the number of drinks in the past year and classified as none (<12 total), light (1-3 per week), or moderate/heavy (>3 per week).