Publications

Introduction

Exposure to secondhand smoke (SHS) is associated with occult obstructive lung disease as evident by abnormal airflow indices representing small airway disease despite having preserved spirometry (normal forced expiratory volume in 1 s-to-forced vital capacity ratio, FEV/FVC). The significance of lung volumes that reflect air trapping in the presence of preserved spirometry is unclear.

Methods

To investigate whether lung volumes representing air trapping could determine susceptibility to respiratory morbidity in people with SHS exposure but without spirometric chronic obstructive pulmonary disease, we examined a cohort of 256 subjects with prolonged occupational SHS exposure and preserved spirometry. We elicited symptom prevalence by structured questionnaires, examined functional capacity (maximum oxygen uptake, VO) by exercise testing, and estimated associations of those outcomes with air trapping (plethysmography-measured residual volume-to-total lung capacity ratio, RV/TLC), and progressive air trapping with exertion (increase in fraction of tidal breathing that is flow limited on expiration during exercise (per cent of expiratory flow limitation, %EFL)).

Results

RV/TLC was within the predicted normal limits, but was highly variable spanning 22%±13% and 16%±8% across the increments of FEV/FVC and FEV, respectively. Respiratory complaints were prevalent (50.4%) with the most common symptom being ≥2 episodes of cough per year (44.5%). Higher RV/TLC was associated with higher OR of reporting respiratory symptoms (n=256; r=0.03; p=0.011) and lower VO (n=179; r=0.47; p=0.013), and %EFL was negatively associated with VO (n=32; r=0.40; p=0.017).

Conclusions

In those at risk for obstruction due to SHS exposure but with preserved spirometry, higher RV/TLC identifies a subgroup with increased respiratory symptoms and lower exercise capacity.

BACKGROUND

Interferon-γ release assays (IGRAs) are important adjunctive tests for diagnosing tuberculosis (TB) disease in children.

METHODS

We analyzed California TB registry data for patients ≤18 years with laboratory-confirmed TB disease during 2010-2015 to identify case characteristics associated with test selection and performance and measure IGRA sensitivity.

RESULTS

In total, 778 cases of TB were reported; 360 were laboratory confirmed. Indeterminate IGRAs were associated with being <1 year old (prevalence rate ratio 9.23; 95% confidence interval 2.87 to 29.8) and having central nervous system disease (prevalence rate ratio 2.69; 95% confidence interval 1.06 to 6.86) on multivariable analysis. Ninety-five children had both an IGRA and tuberculin skin test (TST) performed. Among those, the sensitivity of IGRA in 5- to 18-year-olds was 96% (66 out of 69) vs 83% (57 out of 69) for TST ( = .01); IGRA sensitivity compared with TST in children ages 2 to 4 was 91% (10 out of 11) vs 91% (10 out of 11) ( > .99), and the sensitivity compared with TST in children aged <2 years was 80% (12 out of 15) vs 87% (13 out of 15) ( > .99).

CONCLUSIONS

This is the largest North American analysis of IGRA use and performance among children with TB disease. In children <5 years old, IGRA sensitivity is similar to TST, but sensitivity of both tests are reduced in children <2 years old. Indeterminate results are higher in children <1 year old and in central nervous system disease. In children ≥5 years old with laboratory-confirmed TB, IGRA has greater sensitivity than TST and should be considered the preferred immunodiagnostic test..

Insufficient pre-exposure prophylaxis (PrEP) laboratory monitoring could increase HIV resistance and sexually transmitted infections. We examined test-ordering in a primary care network. Providers did not order HIV testing before almost one-quarter of PrEP initiations; panel management was associated with higher testing. Effective monitoring is needed to maximize PrEP's preventive impact.