***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The AIDS Clinical Trials Group protocol 076 zidovudine prophylaxis regimen for HIV-1-infected pregnant women and their babies has been associated with a significant decrease in vertical HIV-1 transmission in non-breastfeeding women in developed countries . We compared the safety and efficacy of short-course nevirapine or zidovudine during labour and the first week of life . METHODS From November , 1997 , to April , 1999 , we enrolled 626 HIV-1-infected pregnant women at Mulago Hospital in Kampala , Ug and a. We r and omly assigned mothers nevirapine 200 mg orally at onset of labour and 2 mg/kg to babies within 72 h of birth , or zidovudine 600 mg orally to the mother at onset of labour and 300 mg every 3 h until delivery , and 4 mg/kg orally twice daily to babies for 7 days after birth . We tested babies for HIV-1 infection at birth , 6 - 8 weeks , and 14 - 16 weeks by HIV-1 RNA PCR . We assessed HIV-1 transmission and HIV-1-free survival with Kaplan-Meier analysis . FINDINGS Nearly all babies ( 98.8 % ) were breastfed , and 95.6 % were still breastfeeding at age 14 - 16 weeks . The estimated risks of HIV-1 transmission in the zidovudine and nevirapine groups were : 10.4 % and 8.2 % at birth ( p=0.354 ) ; 21.3 % and 11.9 % by age 6 - 8 weeks ( p=0.0027 ) ; and 25.1 % and 13.1 % by age 14 - 16 weeks ( p=0.0006 ) . The efficacy of nevirapine compared with zidovudine was 47 % ( 95 % CI 20 - 64 ) up to age 14 - 16 weeks . The two regimens were well tolerated and adverse events were similar in the two groups . INTERPRETATION Nevirapine lowered the risk of HIV-1 transmission during the first 14 - 16 weeks of life by nearly 50 % in a breastfeeding population . This simple and inexpensive regimen could decrease mother-to-child HIV-1 transmission in less-developed countries Single-dose nevirapine reduces intrapartum human immunodeficiency virus 1 type ( HIV-1 ) transmission but may also select for nonnucleoside reverse-transcriptase inhibitor ( NNRTI ) resistance in breast milk ( BM ) and plasma . Among 32 Zimbabwean women , median 8-week postpartum plasma and BM HIV-1 RNA levels were 4.57 and 2.13 log(10 ) copies/mL , respectively . BM sample s from women with laboratory-diagnosed mastitis ( defined as elevated BM Na(+ ) levels ) were 5.4-fold more likely to have HIV-1 RNA levels above the median . BM RT sequences were not obtained for 12 women with BM HIV-1 RNA levels below the lower limit of detection of the assay used . In 20 paired BM and plasma sample s , 65 % of BM and 50 % of plasma RT sequences had NNRTI-resistance mutations , with divergent mutation patterns To determine the efficacy and safety of 2 inexpensive and easily deliverable antiretroviral ( ARV ) regimens for the prevention of mother-to-child transmission ( MTCT ) of human immunodeficiency virus ( HIV ) type 1 during labor and delivery , HIV-infected pregnant women were screened at 11 maternity health institutions in South Africa and were enrolled in an open-label short course ARV regimen of either nevirapine ( Nvp ) or multiple-dose zidovudine and lamivudine ( Zdv/3TC ) . The overall estimated HIV-1 infection rates in 1307 infants by 8 weeks were 12.3 % ( 95 % confidence interval [ CI ] , 9.7 - 15.0 ) for Nvp and 9.3 % ( 95 % CI , 7.0 - 11.6 ) for Zdv/3TC ( P=.11 ) . Excluding infections detected within 72 h ( intrauterine ) , new HIV-1 infections were detected in 5.7 % ( 95 % CI , 3.7 - 7.8 ) and 3.6 % ( 95 % CI , 2.0 - 5.3 ) of infants in the Nvp and Zdv/3TC groups , respectively , in the 8 weeks after birth . There were no drug-related maternal or pediatric serious adverse events . Common complications were obstetrical for mothers ( Nvp group , 24.3 % ; Zdv/3TC group , 26.3 % ) and respiratory for infants ( Nvp group , 16.1 % ; Zdv/3TC group , 17.0 % ) . This study further confirms the efficacy and safety of short-course ARV regimens in reducing MTCT rates in developing countries BACKGROUND A single dose of nevirapine during labor reduces perinatal transmission of human immunodeficiency virus type 1 ( HIV-1 ) but often leads to viral nevirapine resistance mutations in mothers and infants . METHODS We studied the response to nevirapine-based antiretroviral treatment among women and infants who had previously been r and omly assigned to a single , peripartum dose of nevirapine or placebo in a trial in Botswana involving the prevention of the transmission of HIV-1 from mother to child . All women were treated with antenatal zidovudine . The primary end point for mothers and infants was virologic failure by the 6-month visit after initiation of antiretroviral treatment , estimated within groups by the Kaplan-Meier method . RESULTS Of 218 women who started antiretroviral treatment , 112 had received a single dose of nevirapine and 106 had received placebo .  By the 6-month visit after the initiation of antiretroviral treatment , 5.0 % of the women who had received placebo had virologic failure , as compared with 18.4 % of those who had received a single dose of nevirapine ( P=0.002 ) . Among 60 women starting antiretroviral treatment within 6 months after receiving placebo or a single dose of nevirapine  , no women in the placebo group and 41.7 % in the nevirapine group had virologic failure ( P<0.001 ) . In contrast , virologic failure rates did not differ significantly between the placebo group and the nevirapine group among 158 women starting antiretroviral treatment 6 months or more post partum ( 7.8 % and 12.0 % , respectively ; P=0.39 ) . Thirty infants also began antiretroviral treatment ( 15 in the placebo group and 15 in the nevirapine group ) . Virologic failure by the 6-month visit occurred in significantly more infants who had received a single dose of nevirapine than in infants who had received placebo ( P<0.001 ) . Maternal and infant findings did not change qualitatively by 12 and 24 months after the initiation of antiretroviral treatment . CONCLUSIONS Women who received a single dose of nevirapine to prevent perinatal transmission of HIV-1 had higher rates of virologic failure with subsequent nevirapine-based antiretroviral therapy than did women without previous exposure to nevirapine . However , this applied only when nevirapine-based antiretroviral therapy was initiated within 6 months after receipt of a single , peripartum dose of nevirapine . ( Clinical Trials.gov number , NCT00197587 [ Clinical Trials.gov ] . ) OBJECTIVES To survey the frequency of use of indirect comparisons in systematic review s and evaluate the methods used in their analysis and interpretation . Also to identify alternative statistical approaches for the analysis of indirect comparisons , to assess the properties of different statistical methods used for performing indirect comparisons and to compare direct and indirect estimates of the same effects within review s. DATA SOURCES Electronic data bases . REVIEW METHODS The Data base of Abstract s of Review s of Effects ( DARE ) was search ed for systematic review s involving meta- analysis of r and omised controlled trials ( RCTs ) that reported both direct and indirect comparisons , or indirect comparisons alone . A systematic review of MEDLINE and other data bases was carried out to identify published methods for analysing indirect comparisons . Study design s were created using data from the International Stroke Trial . R and om sample s of patients receiving aspirin , heparin or placebo in 16 centres were used to create meta-analyses , with half of the trials comparing aspirin and placebo and half heparin and placebo . Methods for indirect comparisons were used to estimate the contrast between aspirin  and  heparin . The whole process was repeated 1000 times and the results were compared with direct comparisons and also theoretical results . Further detailed case studies comparing the results from both direct and indirect comparisons of the same effects were undertaken . RESULTS Of the review s identified through DARE , 31/327 ( 9.5 % ) included indirect comparisons . A further five review s including indirect comparisons were identified through electronic search ing . Few review s carried out a formal analysis and some based analysis on the naive addition of data from the treatment arms of interest . Few method ological papers were identified . Some valid approaches for aggregate data that could be applied using st and ard software were found : the adjusted indirect comparison , meta-regression and , for binary data only , multiple logistic regression ( fixed effect models only ) . Simulation studies showed that the naive method is liable to bias and also produces over-precise answers . Several methods provide correct answers if strong but unverifiable assumptions are fulfilled . Four times as many similarly sized trials are needed for the indirect approach to have the same power as directly r and omised comparisons . Detailed case studies comparing direct and indirect comparisons of the same effect show considerable statistical discrepancies , but the direction of such discrepancy is unpredictable . CONCLUSIONS Direct evidence from good- quality RCTs should be used wherever possible . Without this evidence , it may be necessary to look for indirect comparisons from RCTs . However , the results may be susceptible to bias . When making indirect comparisons within a systematic review , an adjusted indirect comparison method should ideally be used employing the r and om effects model . If both direct and indirect comparisons are possible within a review , it is recommended that these be done separately before considering whether to pool data . There is a need to evaluate methods for the analysis of indirect comparisons for continuous data and for empirical research into how different methods of indirect comparison perform in cases where there is a large treatment effect . Further study is needed into when it is appropriate to look at indirect comparisons and when to combine both direct and indirect comparisons . Research into how evidence from indirect comparisons compares to that from non-r and omised studies may also be warranted . Investigations using individual patient data from a meta- analysis of several RCTs using different protocol s and an evaluation of the impact of choosing different binary effect measures for the inverse variance method would also be useful The administration of single-dose nevirapine to women in labor and their infants can prevent HIV-1 mother-to-child transmission . We examined  nevirapine resistance in infants who were HIV-1 infected despite single-dose nevirapine prophylaxis , including 18 Ug and an infants ( HIVNET 012 trial , nine subtype A and nine subtype D ) and 23 Malawian infants ( NVAZ trial , all subtype C ) .  Nevirapine resistance was more frequent in infants with subtype C than with subtypes A and D ( 87 versus 50 % , P = 0.016 ) Objective To examine the emergence and fading of  NVP resistance ( NVPR ) mutations in HIV-1-infected Ug and an women and infants who received single dose NVP to prevent HIV-1 vertical transmission . Design We examined NVPR in women and infants who received NVP in the HIVNET 012 clinical trial , including 41 out of 48 women with infected infants , 70 r and omly-selected women with uninfected infants , and 33 out of 49 infected infants . Methods Plasma HIV-1 was analyzed using the Applied Biosystems ViroSeq HIV-1 Genotyping System . Results NVPR mutations were detected in 21 out of 111 ( 19 % ) women tested 6–8 weeks after delivery . The rate of NVPR was similar among women whose infants were or were not HIV-1 infected . K103N was the most common mutation detected . NVPR mutations faded from detection within 12–24 months in all 11 evaluable women .  High baseline viral load and low baseline CD4 cell count were associated with development of NVPR . NVPR mutations were detected in 11 out of 24 ( 46 % ) evaluable infants who were infected by 6–8 weeks of age . The most common NVPR mutation detected in infants was Y181C . Those mutations faded from detection by 12 months of age in all seven evaluable infants . Of nine evaluable infants with late HIV-1 infection , only one had evidence of NVPR . Conclusions NVPR was detected more frequently in infants than women following NVP prophylaxis , and different patterns of NVPR mutations were detected in women versus infants . NVPR was detected infrequently in infants with late HIV-1 infection .  NVP-resistant HIV-1 faded from detection in women and infants over time Pediatric AIDS Clinical Trials Group protocol 316 was an international , multicenter , place 
    Output:
    
CONCLUSIONS Single-dose NVP is widely used for PMTCT in re source -poor setting s , but the burden of viral resistance is high in both women and children .
It is substantially lower in studies providing additional postpartum antiretrovirals .