Determination of a reference interval in a population.

The reference interval is the most widely used medical decisionmaking tool that separates healthy from diseased individuals. We briefly discuss the methods used to determine reference interval and its limitations.

Mother-to-child transmission of HIV among women who chose not to exclusively breastfeed their infants in Pune, India.

BACKGROUND & OBJECTIVE: The percentage of HIV cases attributed to mother-to-child transmission (MTCT) has increased several fold in recent years. No reports are available on HIV MTCT rates among HIV-infected choosing not be exclusively breastfeed their infants in India. We examined HIV MTCT rates among 41 Indian women in a prospective cohort who chose predominantly not to exclusively breastfeed. METHODS: Of the 41 women, 27 (66%) received MTCT prophylaxis: 3 received short course zidovudine (AZT), 19 single-dose nevirapine (NVP), and 5 both AZT and NVP. Maternal HIV-I RNA levels (viral load) were measured at the time of delivery. Infants were tested for HIV-1 infection by PCR up to 11 times is first year of life and viral load was measured in PCR positive infants. RESULTS: All infants received single dose NVP. Thirty two (76%) infants were exclusively formula-fed, 10 (24%) were mixed fed. Four infants were diagnosed with HIV infection for an overall 12- month transmission probability of 8 per cent [95% confidence interval (CI) of 3.2 to 22.1%]. Restricting analysis to 31 women who exclusively formula-fed, only one (3.1%) transmission event occurred. The 41 HIV-infected women gave birth to 42 live-born infants. INTERPRETATION & CONCLUSION: Our data from a small cohort of HIV-infected women suggest that short-course AZT or single dose NVP are effective in reducing MTCT in an Indian setting. Larger studies are needed to assess HIV MTCT rates in India, but in this small study rates were comparable to that observed among women who chose not to exclusively breastfeed in other resource-limited settings.