ABSTRACT
Chat Generative Pre-Trained Transformer (ChatGPT) is an artificial intelligence (AI) language model developed by OpenAI. It is trained to process vast amounts of text and engage in human-like conversational interaction with users. Being accessible by all, it is widely used and its capabilities range from language translation, summarising long texts and creative writing. This article explores the potential role of ChatGPT in medical education and the possible concerns about the misuse of this technology through a conversation with ChatGPT itself via text prompts. The implications of this technology in medical education as told by ChatGPT are interesting and seemingly helpful for both the students and the tutors. However, this could be a double-edged sword considering the risks of compromised students' integrity and concerns of over-reliance. This also calls for counter strategies and policies in place to mitigate these risks.
Subject(s)
Artificial Intelligence , Education, Medical , Humans , StudentsABSTRACT
The ability to identify lung cancer at an early stage is critical, because it can help patients live longer. However, predicting the affected area while diagnosing cancer is a huge challenge. An intelligent computer-aided diagnostic system can be utilized to detect and diagnose lung cancer by detecting the damaged region. The suggested Linear Subspace Image Classification Algorithm (LSICA) approach classifies images in a linear subspace. This methodology is used to accurately identify the damaged region, and it involves three steps: image enhancement, segmentation, and classification. The spatial image clustering technique is used to quickly segment and identify the impacted area in the image. LSICA is utilized to determine the accuracy value of the affected region for classification purposes. Therefore, a lung cancer detection system with classification-dependent image processing is used for lung cancer CT imaging. Therefore, a new method to overcome these deficiencies of the process for detection using LSICA is proposed in this work on lung cancer. MATLAB has been used in all programs. A proposed system designed to easily identify the affected region with help of the classification technique to enhance and get more accurate results.
Subject(s)
Algorithms , Lung Neoplasms , Humans , Image Processing, Computer-Assisted , Lung , Lung Neoplasms/diagnostic imaging , Tomography, X-Ray ComputedABSTRACT
Triclosan (TCS) is extensively used in healthcare and personal care products as an antibacterial agent. Due to the persistent and toxic nature of TCS, it is not completely degraded in the biological wastewater treatment process. In this research work, identification of TCS degrading bacteria from municipal wastewater sludge and applying the same as bioaugmentation treatment for wastewater have been reported. Based on the 16S rRNA analysis of wastewater sludge, it was found that Providencia rettgeri MB-IIT strain was active and able to grow in higher TCS concentration. The identified bacterial strain was able to use TCS as carbon and energy source for its growth. The biodegradation experiment was optimized for the operational parameters viz. pH (5-10), inoculum size (1-5% (v/v)) and different initial concentration (2, 5, and 10 mg/L) of TCS. During the TCS degradation process, manganese peroxidase (MnP) and laccase (LAC) enzyme activity and specific growth rate of P. rettgeri strain were maximum at pH=7% and 2% (v/v) inoculum size, resulting in 98% of TCS removal efficiency. A total of six intermediate products were identified from the Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis, and the two mechanisms responsible for the degradation of TCS have been elucidated. The study highlights that P. rettgeri MB-IIT strain could be advantageously used to degrade triclosan present in the wastewater.
Subject(s)
Triclosan , Water Pollutants, Chemical , Biodegradation, Environmental , Providencia , RNA, Ribosomal, 16S/genetics , Sewage , Triclosan/analysis , Water Pollutants, Chemical/analysisABSTRACT
The novel finding of Balakrishnan, Miller & Shankar (2008) that investors, overwhelmed by the plethora of stock investment offerings, limit their analysis and daily choices to only a small subset of stocks (i.e., herding behavior) now seems to be common wisdom (Iosebashvili, 2019). We investigate whether the introduction of an innovation in financial products designed to allow investors to trade the entire product bundle of S&P 500 stocks, namely S&P 500 index funds, altered "herding behavior" by creating a new class of index investors. We model the distribution of daily trading concentration as a power law function and examine changes over the last six decades. Intriguingly, we discover a unique pattern in the trading concentration distribution that exhibits two distinct trends. For the period 1960-75, the trading concentration of the S&P 500 stocks tracks the increasing trend for the entire market, i.e., the unevenness in trading has steadily increased. However, after the introduction of S&P 500 index funds in 1975, concentration of trading in the S&P 500 stocks has steadily decreased, i.e., trading distribution has become more even across all 500 stocks, contrary to the current belief of equity analysts. This is also in sharp contrast to the case of U.S. stocks that are not in the S&P 500 index where trading concentration has steadily increased. We further corroborate the uniqueness of the inverted V-shape by a counterfactual investigation of the trading concentration patterns for other sets of 500 stock portfolios. This uniquely distinctive trading concentration pattern for S&P 500 stocks appears to be driven by the increasing dominance of bundle trading by index investors.
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Economics , Investments/economics , Models, Economic , Social Behavior , Decision Making , Financial Management/economics , Humans , Linear Models , Linguistics/trendsABSTRACT
The availability of generic direct acting antivirals (DAAs) for hepatitis C virus (HCV) treatment has prompted many low-and-middle-income countries to launch HCV elimination programs. Because the efficacy of some of these generic DAAs varies by HCV viral subtype, information on subtype distribution can contribute important information to these elimination programs. We conducted a cross-sectional serosurvey to characterize HCV subtype diversity among HIV positive people who inject drugs (PWID) across 14 cities in India. Of 801 HIV positive PWID sampled, 639 tested HCV antibody positive (78.9%). Among 105 samples sequenced, genotype 3 (58.1%) was the most commonly observed followed by genotype 1 (36.2%) and genotype 6 (5.7%). Of the genotype 3 infections, 65% were subtype 3a and 35% were subtype 3b. Of the genotype 1 infections, 94% were subtype 1a and 6% were subtype 1b. All genotype 6 samples were subtype 6n. There was some variability in genotype diversity depending on geographic region and PWID epidemic stage with greater diversity observed in older PWID epidemics. One sequence, HY018, did not cluster with any known reference sequences in phylogenetic analysis. Nearly 80% of HIV infected PWID across India are co-infected with HCV, and subtype prevalence and genetic diversity varied by region and PWID epidemic stage. HCV elimination programs in India will need to consider HCV subtype.
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INTRODUCTION: Anterior cranial fossa (ACF) defects still remains a reconstructive challenge to neurosurgeons due to the difficult location, inaccessibility, and unfavorable vascular anatomy. Usual reconstructive methods reported complications such as recurrent cerebrospinal fluid leak due to bone resorption and tissue breakdown. This is mainly due to the avascularity of the bone graft and inability to provide bony structural support for the skull base. An ideal reconstructive modality should provide a rigid bony support to prevent brain herniation as well as ensure a water tight barrier between sinonasal tract and intracranial compartment. METHODOLOGY: Hence, we thought of a novel technique of taking the outer table of the primary craniotomy flap with its intact myofascial pedicle and moulded it with multiple osteotomies (moulded osteomyofascial pedicled split (MOPS) craniotomy flap) to fit into uneven ACF defects. Advantages of our flap include (1) It is a pedicled vascularized bone flap. (2) It is taken from primary craniotomy flap; hence, no separate craniotomy is required. (3) The inner table is intact and leaves no secondary calvarial bone defect on the donor site. (4) Osteoplastic flap is moulded to fit into the defect, thus providing good contour. RESULTS: MOPS flap was used in five patients with ACF defects due to varied etiologies such as encephalocele defect, frontal mucocele, skull base meningioma, and complex naso ethmoid fracture. Age of the patients included in the study varied from 21 to 60 years. Male:female ratio was 4:1. ACF defects were reconstructed using MOPS flap in all cases. There were no postoperative complications and 1-month postoperative computerized tomography scan showed no evidence of bone resorption with acceptable cosmesis. CONCLUSION: MOPS craniotomy flap provides a novel, easily mastered, and cost-effective technique with minimal complication in reconstruction of complex ACF defects with acceptable esthetic and functional outcome.
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Syndemic theory describes the clustering and synergistic interaction of disease driven by contextual and social factors, which worsen health outcomes for a population, and has been applied to men who have sex with men (MSM) and their risk for HIV and other sexually transmitted infections. Recent reviews, however, have critiqued prevailing approaches in syndemic studies that assess only additive associations without evaluation of synergy. Following these suggestions, we compared the traditional additive approach with a test for synergistic association of 5 syndemic conditions (alcohol dependence, illicit drug use, depression, intimate partner violence (IPV), and childhood sexual abuse (CSA)) with unprotected anal intercourse (UAI) and active syphilis infection among 11,771 MSM recruited through respondent driven sampling from 12 cities in India. UAI was assessed via self-report and active syphilis infection was diagnosed by RPR and THPA tests. An additive association was explored using a condition count (range 0-5), and synergy was tested using relative excess risk due to interactions (RERIs) calculated from all 2-way and common 3-way interactions between conditions in adjusted regression models. There was a significant dose response associated with the syndemic count and UAI, and a similar pattern for syphilis, though not statistically significant. RERIs showed synergy for only one pair of conditions for UAI and syphilis, respectively: IPV + depression and alcohol dependence + illicit drug use. In this study, we found an additive association between syndemic conditions and UAI with evidence of synergistic interaction between a pair of psychosocial conditions, and no significant additive association, but a synergistic interaction between another pair of psychosocial conditions for syphilis. Our results lend further support to a critical reassessment of syndemic analyses. Closer attention to the cumulative development, underlying causal pathways, and possible synergistic interaction of co-occurring epidemics through combined qualitative and quantitative methodologies may yield more effective interventions for vulnerable, marginalized populations.
Subject(s)
Epidemics , Homosexuality, Male/psychology , Risk-Taking , Sexual Behavior/psychology , Social Environment , Adult , Adult Survivors of Child Abuse/statistics & numerical data , Alcoholism/epidemiology , Comorbidity , Depression/epidemiology , Homosexuality, Male/statistics & numerical data , Humans , India/epidemiology , Intimate Partner Violence/statistics & numerical data , Male , Risk Factors , Social Theory , Substance-Related Disorders/epidemiology , Syphilis/epidemiology , Unsafe Sex/statistics & numerical dataABSTRACT
The study aimed to determine the prevalence of occult hepatitis B virus infection among HIV-infected persons and to evaluate the use of a pooling strategy to detect occult HBV infection in the setting of HIV infection. Five hundred and two HIV-positive individuals were tested for HBV, occult HBV and hepatitis C and D with serologic and nucleic acid testing (NAT). We also evaluated a pooled NAT strategy for screening occult HBV infection among the HIV-positive individuals. The prevalence of HBV infection among HIV-positive individuals was 32 (6.4%), and occult HBV prevalence was 10%. The pooling HBV NAT had a sensitivity of 66.7% and specificity of 100%, compared to HBV DNA NAT of individual samples. In conclusion, this study found a high prevalence of occult HBV infection among our HIV-infected population. We also demonstrated that pooled HBV NAT is highly specific, moderately sensitive and cost-effective. As conventional HBV viral load assays are expensive in resource-limited settings such as India, pooled HBV DNA NAT might be a good way for detecting occult HBV infection and will reduce HBV-associated complications.
Subject(s)
DNA, Viral/isolation & purification , HIV Infections/complications , Hepatitis B virus/isolation & purification , Hepatitis B/diagnosis , Hepatitis B/epidemiology , Molecular Diagnostic Techniques/methods , Specimen Handling/methods , Adult , Female , Hepatitis C/diagnosis , Hepatitis C/epidemiology , Hepatitis D/diagnosis , Hepatitis D/epidemiology , Humans , India/epidemiology , Male , Sensitivity and SpecificityABSTRACT
INTRODUCTION: Tumours of central nervous system constitute 1%-2% of tumours in adults. The incidence of brain tumours has been reported to be around 3.9 and 3.0/one lac/year in males and females respectively. A few studies are available from India which show a lower incidence of brain tumours compared to the developed countries. Not much is known about the epidemiology of brain tumours in the population from South India. AIM: To identify the age groups, gender distribution, topography and different histological types of brain tumours. MATERIALS AND METHODS: A total of 510 cases of brain tumours were identified over a period of seven years which were included in the present study. We retrieved the slides of these cases and reviewed them. Immunohistochemistry in required cases were done. Age and gender distribution, clinical presentation, site of tumour and histopathologic patterns with grade were noted and the data was analysed with SPSS software version 17.0. RESULTS: Our analysis showed that most of the brain tumours occur between 40-60 years of age, with a male to female ratio of 0.9:1. Majority of cases involved dura and cerebral lobes except for the occipital lobe, and meningioma and glial tumours were the most common broad histological types. WHO grade IV tumours and metastasis were common in males compared to females. CONCLUSION: This study revealed the distribution of brain tumours in patients attending our institution. The results obtained were comparable with available worldwide data.
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Cadmium (Cd) is an environmental pollutant that has been associated with cardiovascular disease in populations, but the relationship of Cd with hypertension has been inconsistent. We studied the association between urinary Cd concentrations, a measure of total body burden, and blood pressure in American Indians, a US population with above national average Cd burden. Urinary Cd was measured using inductively coupled plasma mass spectrometry, and adjusted for urinary creatinine concentration. Among 3714 middle-aged American Indian participants of the Strong Heart Study (mean age 56 years, 41% male, 67% ever-smokers, 23% taking antihypertensive medications), urinary Cd ranged from 0.01 to 78.48 µg g-1 creatinine (geometric mean=0.94 µg g-1) and it was correlated with smoking pack-year among ever-smokers (r2=0.16, P<0.0001). Participants who were smokers were on average light-smokers (mean 10.8 pack-years), and urinary Cd was similarly elevated in light- and never-smokers (geometric means of 0.88 µg g-1 creatinine for both categories). Log-transformed urinary Cd was significantly associated with higher systolic blood pressure in models adjusted for age, sex, geographic area, body mass index, smoking (ever vs never, and cumulative pack-years) and kidney function (mean blood pressure difference by lnCd concentration (ß)=1.64, P=0.002). These associations were present among light- and never-smokers (ß=2.03, P=0.002, n=2627), although not significant among never-smokers (ß=1.22, P=0.18, n=1260). Cd was also associated with diastolic blood pressure among light- and never-smokers (ß=0.94, P=0.004). These findings suggest that there is a relationship between Cd body burden and increased blood pressure in American Indians, a population with increased cardiovascular disease risk.
Subject(s)
Blood Pressure , Cadmium/urine , Hypertension/urine , Indians, North American/statistics & numerical data , Body Burden , Cross-Sectional Studies , Female , Humans , Male , Middle AgedABSTRACT
AIM: To investigate the genetic influence of circulating lactate level, a marker of oxidative capacity associated with diabetes. METHODS: We conducted a genome-wide association study of log-transformed plasma lactate levels in 6901 European-American participants in the Atherosclerosis Risk in Communities study. For regions that achieved genome-wide significance in European-American participants, we conducted candidate region analysis in African-American subjects and tested for interaction between metformin use and the index single nucleotide polymorphisms for plasma lactate in European-American subjects. RESULTS: The genome-wide association study in European-American subjects identified two genome-wide significant loci, GCKR (rs1260326, T allele ß=0.08; P=1.8×10(-47) ) and PPP1R3B/LOC157273 (rs9987289, A allele ß=0.06; P=1.6×10(-9) ). The index single nucleotide polymorphisms in these two loci explain 3.3% of the variance in log-transformed plasma lactate levels among the European-American subjects. In the African-American subjects, based on a region-significant threshold, the index single nucleotide polymorphism at GCKR was associated with plasma lactate but that at PPP1R3B/LOC157273 was not. Metformin use appeared to strengthen the association between the index single nucleotide polymorphism at PPP1R3B/LOC157273 and plasma lactate in European-American subjects (P for interaction=0.01). CONCLUSIONS: We identified GCKR and PPP1R3B/LOC157273 as two genome-wide significant loci of plasma lactate. Both loci are associated with other diabetes-related phenotypes. These findings increase our understanding of the genetic control of lactate metabolism.
Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Lactic Acid/blood , Protein Phosphatase 1/genetics , Black or African American , Alleles , Cohort Studies , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/drug therapy , Female , Genome-Wide Association Study , Humans , Hypoglycemic Agents/therapeutic use , Male , Metformin/therapeutic use , Middle Aged , Phenotype , Polymorphism, Single Nucleotide , White PeopleABSTRACT
BACKGROUND: The converging epidemics of HIV and tuberculosis (TB) pose one of the greatest public health challenges of our time. Rapid diagnosis of TB is essential in view of its infectious nature, high burden of cases, and emergence of drug resistance. OBJECTIVE: The purpose of this present study was to evaluate the feasibility of implementing the microscopic observation drug susceptibility (MODS) assay, a novel assay for the diagnosis of TB and multi-drug-resistant tuberculosis (MDR-TB) directly from sputum specimens, in the Indian setting. MATERIALS AND METHODS: This study involved a cross-sectional, blinded assessment of the MODS assay on 1036 suspected cases of pulmonary TB in HIV-positive and HIV-negative patients against the radiometric method, BD-BACTEC TB 460 system. RESULTS: Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of the MODS assay in detecting MTB among TB suspected patients were 89.1%, 99.1%, 94.2%, 95.8%, respectively. In addition, in the diagnosis of drug-resistant TB, the MODS assay was 84.2% sensitive for those specimens reporting MDR, 87% sensitivity for those specimens reporting INH mono-resistance, and 100% sensitive for specimens reporting RIF mono-resistance. The median time to detection of TB in the MODS assay versus BACTEC was 9 versus 21 days (P<0.001). CONCLUSION: Costing 5 to 10 times lesser than the automated culture methods, the MODS assay has the potential clinical utility as a simple and rapid method. It could be effectively used as an alternative method for diagnosing TB and detection of MDR-TB in a timely and affordable way in resource-limited settings.
Subject(s)
Antitubercular Agents/pharmacology , Drug Resistance, Bacterial , HIV Infections/complications , Microscopy/methods , Mycobacterium tuberculosis/isolation & purification , Tuberculosis/diagnosis , Tuberculosis/microbiology , Adult , Costs and Cost Analysis , Humans , India , Male , Microbial Sensitivity Tests/economics , Microbial Sensitivity Tests/methods , Microscopy/economics , Mycobacterium tuberculosis/drug effects , Predictive Value of Tests , Sensitivity and Specificity , Sputum/microbiologyABSTRACT
A collection of 1,108 case-parent trios ascertained through an isolated, nonsyndromic cleft lip with or without cleft palate (CL/P) was used to replicate the findings from a genome-wide association study (GWAS) conducted by Beaty et al. (Nat Genet 42:525-529, 2010), where four different genes/regions were identified as influencing risk to CL/P. Tagging SNPs for 33 different genes were genotyped (1,269 SNPs). All four of the genes originally identified as showing genome-wide significance (IRF6, ABCA4 and MAF, plus the 8q24 region) were confirmed in this independent sample of trios (who were primarily of European and Southeast Asian ancestry). In addition, eight genes classified as 'second tier' hits in the original study (PAX7, THADA, COL8A1/FILIP1L, DCAF4L2, GADD45G, NTN1, RBFOX3 and FOXE1) showed evidence of linkage and association in this replication sample. Meta-analysis between the original GWAS trios and these replication trios showed PAX7, COL8A1/FILIP1L and NTN1 achieved genome-wide significance. Tests for gene-environment interaction between these 33 genes and maternal smoking found evidence for interaction with two additional genes: GRID2 and ELAVL2 among European mothers (who had a higher rate of smoking than Asian mothers). Formal tests for gene-gene interaction (epistasis) failed to show evidence of statistical interaction in any simple fashion. This study confirms that many different genes influence risk to CL/P.
Subject(s)
Asian People/genetics , Cleft Lip/genetics , Cleft Palate/genetics , Genetic Linkage , Genome-Wide Association Study/methods , Polymorphism, Single Nucleotide , White People/genetics , Female , Humans , Male , Meta-Analysis as TopicABSTRACT
PURPOSE: Human immunodeficiency virus (HIV) diagnostic tests are being used extensively in India. However, the evaluation data on these assays are very limited. The present study evaluates indigenous HIV test kits manufactured in India. MATERIALS AND METHODS: A total of 200 characterised specimens were assayed with Comb AIDS - RS Advantage HIV 1+2 Immunodot Test, Enzaids HIV 1+2 ELISA test, Enzaids Duet HIV Antigen+antibody ELISA test and Signal HIV Flow Through HIV 1+2 test kits. Performance characteristics of these assays were calculated. RESULTS: Sensitivity, specificity, positive predictive value, negative predictive value and efficiency of all the assays were 100% except for Signal HIV Flow Through HIV 1+2 test kit. The specificity, positive predictive value and efficiency of the Signal HIV Flow Through HIV 1+2 test kit were 98.9%, 98.9% and 99.4%, respectively. The Enzaids Duet HIV kit was found to be extremely sensitive in detecting p24 Ag with the sensitivity of 1.5 pg/mL. CONCLUSIONS: To conclude, selection of better diagnostic assay is very much important to resolve discrepancies in HIV diagnosis. All these assays under evaluation in this report have got excellent performance characteristics and much suitable to use in serial testing algorithms in use for resources limited settings.
Subject(s)
Clinical Laboratory Techniques/methods , HIV Infections/diagnosis , HIV-1/immunology , Enzyme-Linked Immunosorbent Assay/methods , Humans , India , Predictive Value of Tests , Sensitivity and Specificity , Time FactorsABSTRACT
To review a quality control and quality assurance (QC/QA) model established to ensure the validity and reliability of collection, storage and analysis of biological outcome data, and to promote good laboratory practices (GLPs) and sustained operational improvements in international clinical laboratories, we conducted a two-arm randomized community-level HIV behavioural intervention trial in five countries: China, India, Peru, Russia and Zimbabwe. The trial was based on diffusion theory utilizing a Community Popular Opinion Leaders (CPOLs) intervention model with behavioural and biological outcomes. The QC/QA model was established by the Biological Outcome Workgroup, which collaborated with the Data Coordinating Center and John Hopkins University Reference Laboratory. Five international laboratories conducted chlamydia/gonorrhoea polymerase chain reaction (PRC)-based assays, herpes simplex virus type 2 enzyme immunoassay (EIA), syphilis serology (rapid plasma regain and Treponema pallidum particle agglutination assay, HIV serology (EIA/Western blot) and Trichomonas vaginalis culture. Data were collected at baseline, 12 and 24 months. Laboratory performance and infrastructure improved throughout the trial. Recommendations for improvement were consistently followed. Quality laboratories in resource-poor settings can be established, operating standards can be improved and certification can be obtained with consistent training, monitoring and technical support. Building collaborative partnership relations can establish a sustainable network for clinical trials, and can lead to accreditation and international laboratory development.
Subject(s)
Clinical Laboratory Techniques/methods , Clinical Laboratory Techniques/standards , International Cooperation , Sexually Transmitted Diseases/diagnosis , Adolescent , Adult , Behavior Therapy/methods , Developing Countries , Female , Humans , Male , Middle Aged , Quality Control , Young AdultABSTRACT
The aim of the article is to compare the clinical and behavioural characteristics of HIV-infected South Indian patients in concordant and discordant heterosexual relationships. A cross-sectional analysis of married couples in concordant and discordant relationships was carried out. Demographic and clinical characteristics, sexual behaviours, CD4 cell count and plasma HIV-1 RNA loads were assessed. A total of 839 concordant patients and 996 discordant patients were included in this analysis. Significantly more men were in discordant than concordant relationships (97% versus 59%; P = 0.002). More discordant patients had never initiated highly active antiretroviral treatment (HAART) than concordant patients (14.1% versus 8.5%; P = 0.004). Concordant patients had significantly higher CD4 cell counts than discordant patients at the time of enrolling to care (205 versus 139 cells/microL; P = 0.001). Discordant patients had significantly higher plasma viral loads than concordant patients (100,000 copies/mL versus 89,154 copies/mL; P = 0.002). Discordant patients were more likely to use condoms with their spouses than concordant patients (49% versus 28.8%; P = 0.01). In conclusion, couples-based interventions and the provision of HAART could substantially decrease behavioural and clinical correlates of HIV transmission among discordant South Indian married couples. The spouses of HIV-infected index patients are at increased risk for HIV infection, and further preventive measures are needed.
Subject(s)
Disease Transmission, Infectious/prevention & control , Family Characteristics , HIV Infections/psychology , HIV-1 , Sexual Behavior , Adult , Anti-HIV Agents/therapeutic use , Antiretroviral Therapy, Highly Active , CD4 Lymphocyte Count , Cross-Sectional Studies , Female , HIV Infections/immunology , HIV Infections/virology , Heterosexuality , Humans , India/epidemiology , Male , Risk Factors , Risk-Taking , Viral LoadABSTRACT
OBJECTIVE: To assess the risk factors associated with heterosexual HIV transmission among South Indian discordant couples enrolled in clinical care. METHODS: A nested matched case-control study of serodiscordant couples in which the HIV-infected partner (index case) was enrolled in care. Demographic and clinical characteristics, sexual behaviours, CD4 cell count and plasma HIV-1 RNA loads were measured at enrollment and longitudinally over 12 months of follow-up. The study included 70 cases who seroconverted during study follow-up and 167 matched controls who remained persistently serodiscordant. RESULTS: The incidence of HIV infection among the initially seronegative partners was 6.52 per 100 person-years. Persistently discordant patients were more likely to have initiated highly active antiretroviral therapy (HAART) than patients in seroconverting relationships (62.9%vs. 42.9%) (P=0.001). Patients in seroconverting relationships had significantly higher plasma viral loads (PVLs) than patients in discordant relationships at enrolment, at 6 months and at 12 months (P<0.05). Patients in seroconverting relationships were less likely to use condoms with their primary partners than patients in discordant relationships (P<0.05). Patients in relationships that seroconverted between 6 and 12 months were diagnosed more often with genital Herpes simplex than patients in discordant relationships (P=0.001). In the univariate and multivariate logistic regression, the following variables were associated with seroconversion: PVL >100,000 [odds ratio (OR): 1.82; 95% confidence interval (CI): 1.1-2.8], non-disclosure of HIV status (OR: 5.5; 95% CI: 4.3-6.2) and not using condoms (OR: 2.8; 95% CI: 2.4-3.6). CONCLUSIONS: Couples-based intervention models are crucial in preventing HIV transmission to seronegative spouses. Providing early treatment for sexually transmitted infections, HAART and enhancing condom use and disclosure could potentially decrease the risk of HIV transmission within Indian married couples.