Normal values of respiratory oscillometry in South African children and adolescents.

Introduction: Noninvasive measurement of respiratory impedance by oscillometry can be used in young children aged from 3 years and those unable to perform forced respiratory manoeuvres. It can discriminate between healthy children and those with respiratory disease. However, its clinical application is limited by the lack of reference data for African paediatric populations. The aim of the present study was to develop reference equations for oscillometry outcomes in South African children and adolescents. Methods: Healthy subjects, enrolled in the Drakenstein Child Health Study, HIV-uninfected adolescents in the Cape Town Adolescent Antiretroviral Cohort and healthy children attending surgical outpatient clinics at Red Cross War Memorial Children's Hospital were measured with conventional spectral (6-32 Hz) and intra-breath (10 Hz) oscillometry. Stepwise linear regression was used to assess the relationship between respiratory variables and anthropometric predictors (height, sex, ancestry) to generate reference equations. Results: A total of 692 subjects, 48.4% female, median age of 5.2 years (range: 3-17 years) were included. The median (interquartile range (IQR)) for weight for age z-score and height for age z-score was -0.42 (-1.11-0.35) and -0.65 (-1.43-0.35), respectively. Stepwise regression demonstrated that all the variables were significantly dependent on height only. Comparison to previous reference data indicated slightly higher resistance and lower compliance values in the smallest children. Conclusion: We established the first respiratory oscillometry reference equations for African children and adolescents, which will facilitate use in early identification and management of respiratory disease. Our results suggest differences in oscillometry measures by ancestry but also highlight the lack of standardisation in methodology.

Longitudinal Changes in Spirometry in South African Adolescents Perinatally Infected With Human Immunodeficiency Virus Who Are Receiving Antiretroviral Therapy.

BACKGROUND: Despite increased access to highly active antiretroviral therapy (HAART), lung disease remains common in human immunodeficiency virus (HIV)-infected (HIV+) adolescents. There is limited information on changes in lung function over time in perinatally HIV+ adolescents on HAART. The objective was to investigate the progression of spirometry findings over 2 years in HIV+ adolescents on HAART in a prospective cohort, the Cape Town Adolescent Antiretroviral Cohort (CTAAC). METHODS: HIV+ adolescents aged 9-14 years, with at least 6 months of HAART, and a comparator group of healthy HIV-uninfected (HIV-), age-matched controls were enrolled in CTAAC. Spirometry and bronchodilator testing were done at baseline, 12 months, and 24 months. Mixed-effect models were used to compute longitudinal changes in lung function. RESULTS: Five hundred fifteen HIV+ adolescents, mean age 12 (standard deviation [SD], 1.6) years, 50.4% male, and 110 HIV- adolescents, mean age 11.8 (SD, 1.8) years, 45.6% male, were tested at baseline; 477 (93%) HIV+ and 102 (93%) HIV- adolescents at 12 months; and 473 (92%) HIV+ and 97 (88%) HIV- adolescents at 24 months. Only 5.4% of the HIV+ adolescents had HIV viral load >10 000 copies/mL at baseline. Forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were lower in the HIV+ compared to the HIV- adolescents and tracked with no deterioration or catch-up over 2 years. Previous pulmonary tuberculosis (PTB) or lower respiratory tract infection (LRTI) was significantly associated with reduced FEV1 and FVC (P < .05 for both). CONCLUSIONS: HIV+ adolescents had lower lung function over 2 years than HIV- adolescents. This study highlights the need for lung function surveillance and prevention of LRTIs and PTB in HIV+ adolescents.

Lung Function in South African Adolescents Infected Perinatally with HIV and Treated Long-Term with Antiretroviral Therapy.

RATIONALE: Lung disease is a common cause of mortality and morbidity in HIV-infected adolescents, but there is limited information on the spectrum of lung function impairment in adolescents on antiretroviral therapy. OBJECTIVES: To investigate lung function in HIV-infected adolescents on antiretroviral therapy in the Cape Town Adolescent Antiretroviral Cohort (Cape Town, South Africa). METHODS: A total of 515 South African adolescents, aged 9-14 years, stable on antiretroviral therapy for at least 6 months, underwent baseline lung function testing. Measures included spirometry, nitrogen multiple-breath washout, forced oscillation technique, 6-minute walk test, single-breath carbon monoxide diffusion testing, and bronchodilator response testing. A comparator group of 110 age- and ethnicity-matched HIV-uninfected adolescents was also tested. RESULTS: For the HIV-infected adolescents (mean [SD] age 12 [1.6] years, 52% male), the median (interquartile range) duration of antiretroviral therapy was 7.6 (4.6-9.2) years. The median (interquartile range) nadir CD4 was 510.5 (274-903) cells/mm3. HIV-infected adolescents had significantly lower FEV1, FVC, FEV1/FVC, diffusing capacity of carbon monoxide, respiratory system compliance, and functional residual capacity than HIV-uninfected adolescents (P < 0.05 for all associations). HIV-infected adolescents had higher airway resistance and lung clearance index than HIV-uninfected adolescents (P < 0.05 for all associations). Although generally small in magnitude, these differences remained significant after adjusting for age, sex, and height. In addition, age, sex, height, and history of past lower respiratory tract infection or pulmonary tuberculosis were associated with reduced lung function. CONCLUSIONS: Perinatally infected South African HIV-infected adolescents on antiretroviral therapy have lower lung function than uninfected adolescents. Prior lower respiratory tract infection or pulmonary tuberculosis is associated with lower lung function.