Table 1.
Baseline Characteristics of Index Tuberculosis Patients, Households, and Household Contacts, Lima, Peru, September 2009–August 2012 (N = 14 044)
| Characteristic | Traininga | Validationb | P Value |
|---|---|---|---|
| No. of household contacts | 10 062 | 3982 | |
| Index TB patient characteristics | |||
| Female sex | 41.5 | 39.4 | .02 |
| Age, y | |||
| Median (IQR) | 27 (21–41) | 28 (21–44) | .09 |
| 16–30 | 58.8 | 57.0 | < .001 |
| 31–45 | 20.2 | 19.1 | |
| 46–60 | 10.8 | 11.4 | |
| > 60 | 10.1 | 12.5 | |
| College education or higher | 28.8 | 23.7 | < .001 |
| Smoking | |||
| None | 97.4 | 97.0 | < .001 |
| ≤ 1 cigarette a day | 1.3 | 0.8 | |
| > 1 cigarette a day | 1.3 | 2.2 | |
| Living with HIV | 3.8 | 4.9 | .003 |
| TB history | 17.7 | 17.2 | .52 |
| Cavitary disease | 24.0 | 28.2 | < .001 |
| Smear positive | 63.4 | 71.0 | < .001 |
| Culture positive | 80.2 | 85.5 | < .001 |
| Diagnostic delay ≥ 4 wk | 45.8 | 43.2 | .007 |
| Season of diagnosis | |||
| Spring (September–November) | 27.3 | 27.5 | < .001 |
| Summer (December–February) | 24.8 | 28.5 | |
| Fall (March–May) | 26.3 | 23.9 | |
| Winter (June–August) | 21.7 | 20.1 | |
| Symptom of coughing | 85.4 | 87.8 | < .001 |
| Household characteristics | |||
| Socioeconomic status | |||
| Low | 32.9 | 38.9 | < .001 |
| Medium | 46.4 | 38.3 | |
| High | 20.7 | 22.8 | |
| Crowding > 4 people per room | 19.6 | 29.9 | < .001 |
| Type of housing | |||
| House | 12.2 | 26.7 | < .001 |
| Apartment | 82.5 | 51.6 | |
| Other | 5.3 | 21.8 | |
| Household TB history | 39.3 | 42.5 | .001 |
| Contact characteristics | |||
| Relationship between the contact and the index patient | |||
| Child of index patient | 19.0 | 19.3 | .11 |
| Parent | 15.0 | 14.1 | |
| Sibling | 20.9 | 19.4 | |
| Spouse | 7.6 | 8.1 | |
| Other | 37.6 | 39.0 | |
| Male sex | 44.9 | 44.2 | .48 |
| Age, y | |||
| Median (IQR) | 23 (11–41) | 24 (10–43) | .05 |
| <5 | 12.6 | 13.2 | < .001 |
| 5–19 | 30.5 | 28.7 | |
| 20–30 | 19.2 | 19.2 | |
| 31–45 | 18.4 | 16.6 | |
| 46–60 | 13.1 | 13.4 | |
| > 60 | 6.3 | 8.8 | |
| College education or higherd | 30.5 | 29.7 | .50 |
| Smokingd | |||
| None | 90.2 | 88.6 | .11 |
| ≤ 1 cigarette a day | 5.1 | 5.9 | |
| > 1 cigarette a day | 4.7 | 5.5 | |
| Drinkingd | |||
| None | 58.6 | 61.3 | .07 |
| ≤ 2 units per day | 32.8 | 30.3 | |
| > 2 units per day | 8.6 | 8.4 | |
| Self-reported diabetes | 1.5 | 2.4 | .001 |
| Living with HIV | 0.4 | 0.5 | .26 |
| Nutritionc | |||
| Normal | 58.2 | 55.8 | .02 |
| Underweight | 1.9 | 1.8 | |
| Overweight | 39.9 | 42.4 | |
| BMId, kg/m2, mean (SD) | 26.7 (4.7) | 27.0 (5.1) | .03 |
| TB history | 7.5 | 8.1 | .23 |
| No. of BCG scars | |||
| 0 | 13.5 | 14.9 | < .001 |
| 1 | 63.1 | 66.0 | |
| 2 | 18.4 | 16.1 | |
| ≥ 3 | 5.0 | 2.9 | |
| Cough | |||
| None | 90.5 | 92.1 | .007 |
| 1–7 d | 3.1 | 2.8 | |
| 8–14 d | 0.5 | 0.5 | |
| 15–30 d | 5.1 | 3.7 | |
| > 30 d | 0.8 | 0.8 | |
| Tuberculin skin test | |||
| TST contraindicated | 12.1 | 19.9 | < .001 |
| < 5 mm | 42.4 | 34.4 | |
| 5–9 mm | 12.1 | 9.9 | |
| 10–14 mm | 21.7 | 20.9 | |
| ≥ 15 mm | 11.6 | 14.9 | |
| Endpoints | |||
| Coprevalent TB | 2.0 | 2.5 | .08 |
| 1-y incident TB | 2.1 | 2.3 | .38 |
| 1-y incident TBd | 1.8 | 2.1 | .43 |
Data are presented as percentage unless otherwise indicated. P values were based on χ 2 tests for categorical variables, Wilcoxon rank-sum test for continuous variables with nonnormal distributions (age of index patient and age of contact), and t test with equal variance for BMI.
Abbreviations: BCG, bacille Calmette Guerin; BMI, body mass index; HIV, human immunodeficiency virus; IQR, interquartile range; SD, standard deviation; TB, tuberculosis; TST, tuberculin skin test.
aWe trained the models on the subset of contacts with index patients diagnosed in North Lima, East Lima, and Rimac.
bWe validated the models among the subset of contacts diagnosed within central Lima. Using a geographically external sample for validation allows our models to be tested in demographically different households than those represented by the training sample.
cNutrition was defined as follows: Underweight: for under-5, z score for weight for length/height ≤ −2 from World Health Organization (WHO) mean; for age 5–19: z score for BMI for age ≤ −2 from WHO mean; for age ≥20: BMI <18.5 kg/m2. Overweight: for under-5, z score for weight for length/height >2 from WHO mean; for age 5–19: z score for BMI for age >2 from WHO mean; for age ≥20: BMI ≥25 kg/m2. Normal: otherwise. Using weight for length may result in an underestimation in the prevalence of underweight for infants aged <2 years, particularly in settings with high burden of stunting.
dFor adults (≥20 years of age) only.