Pre-sensitization with tuberculosis and non-tuberculosis mycobacteria and its impact on TB incidence in different age groups: Chengalpattu BCG trial revisited.

Individuals pre-sensitized with Mycobacterium tuberculosis (MTB), non-tuberculosis mycobacteria, and its impact on TB incidence are relatively unexplored in a high TB burden setting. We conducted secondary data analysis of a double-blind, randomized Chengalpattu BCG trial, India. Induration to Purified Protein Derivative (PPD)-S and PPD-B were proxies for exposures to MTB and M. intracellulare respectively. Optimum cut-off for PPD-S and B were determined using Receiver-Operating Characteristic curves and induration ≥12 mm for PPD-S and ≥10 mm for PPD-B were considered strong reaction. Incidence rates of culture positive pulmonary TB per 100,000 person-years (PY) were calculated. Of 270,043 individuals with skin test results, children <14 years (n = 109,383, 64% showed strong-reaction to PPD-B and 17% to PPD-S) and adults between 25 and 34 years (n = 40,292, 98% were strong reactors to PPD-B and 73% to PPD-S). Overall incidence rate was lower in individuals with PPD-S < PPD-B (136, 95% CI: 130-141/100,000 PY) compared to individuals with PPD-S > PPD-B (447, 95% CI: 427-468/100,000 PY). Incidence rates of culture positive pulmonary TB was affected by early age of exposure to cross-reactive mycobacterial antigens represented by PPD-B and exposure to MTB represented by PPD-S during adolescence and early adulthood.

Timing of Mycobacterium tuberculosis exposure explains variation in BCG effectiveness: a systematic review and meta-analysis.

RATIONALE: The heterogeneity in efficacy observed in studies of BCG vaccination is not fully explained by currently accepted hypotheses, such as latitudinal gradient in non-tuberculous mycobacteria exposure. METHODS: We updated previous systematic reviews of the effectiveness of BCG vaccination to 31 December 2020. We employed an identical search strategy and inclusion/exclusion criteria to these earlier reviews, but reclassified several studies, developed an alternative classification system and considered study demography, diagnostic approach and tuberculosis (TB)-related epidemiological context. MAIN RESULTS: Of 21 included trials, those recruiting neonates and children aged under 5 were consistent in demonstrating considerable protection against TB for several years. Trials in high-burden settings with shorter follow-up also showed considerable protection, as did most trials in settings of declining burden with longer follow-up. However, the few trials performed in high-burden settings with longer follow-up showed no protection, sometimes with higher case rates in the vaccinated than the controls in the later follow-up period. CONCLUSIONS: The most plausible explanatory hypothesis for these results is that BCG protects against TB that results from exposure shortly after vaccination. However, we found no evidence of protection when exposure occurs later from vaccination, which would be of greater importance in trials in high-burden settings with longer follow-up. In settings of declining burden, most exposure occurs shortly following vaccination and the sustained protection observed for many years thereafter represents continued protection against this early exposure. By contrast, in settings of continued intense transmission, initial protection subsequently declines with repeated exposure to Mycobacterium tuberculosis or other pathogens.

Prevalence of Hypertension among Urban Poor with and without Diabetes - A Study from South India.

OBJECTIVE: Hypertension and Diabetes are considered as two leading risk factors of mortality in the world. According to an ICMR-INDIAB study, prevalence of hypertension in Tamil Nadu was higher in urban population than the rural population. Hence this study was planned to estimate the prevalence and distribution of hypertension among the urban poor with and without diabetes. METHODS: A community based cross-sectional study was conducted among two backward communities in North Chennai, Tamil Nadu. A total of 330 participants with and without diabetes, were recruited after screening 1272 subjects and self reported diabetes cases of 235. Measurement of blood pressure was done in both groups based on American Heart Association (AHA) criteria and diagnosis of diabetes was made based on the previous history of diabetes and WHO criteria. RESULTS: Prevalence of hypertension (Stage II) among the people with diabetes and without diabetes was reported 44.8%, and 42.6% respectively (p= 0.046). Obesity and overweight were significantly associated with prevalence of hypertension among people with diabetes (p= 0.021). Distribution of stage II hypertension among males and females were 46.2% and 42.80% respectively. There was significant gender difference in the prevalence of HTN (p = 0.043). CONCLUSION: Prevalence of hypertension was found to be higher among the diabetic group compared to the non- diabetic group (44.8% vs 42.6%), though the difference between the two was not very substantial. We therefore conclude that half of the urban poor are hypertensive even if they are not diabetic.

Prevalence of Diabetes Mellitus and Exposure to Suspended Particulate Matter.

BACKGROUND: Evidence from various epidemiological studies has shown an association between particulate matter 2.5 (PM2.5) and diabetes mellitus. A prospective study from the United States reported that exposure to PM2.5 alters endothelial function, and leads to insulin resistance and reduction in peripheral glucose uptake. There is a paucity of data on the relation between air pollution and diabetes in low- and middle-income countries. OBJECTIVES: To estimate the prevalence of type 2 diabetes among people living in areas with higher exposures of suspended PM2.5 compared to people living in areas with lower exposures in Chennai, Tamil Nadu, India. METHODS: A cross-sectional study was carried out in two areas of Chennai city. The PM2.5 affecting vulnerable areas were stratified from a list of air quality monitoring stations in Tamil Nadu Pollution Control Board and Central Pollution Control Board. The highest and lowest areas of exposure were selected from the list. Households were randomly selected for the study. A total of 201 (67 male, 134 female) individuals from a high exposure area (HEA) and 209 (76 male 133 female) individuals from a low exposure area (LEA) were recruited for the study. Adults over 18 years of age were screened for random capillary blood glucose (RCBG) by glucometer (OneTouch Ultra). RESULTS: The prevalence of diabetes (34.8% vs 19.6% p =0.001) was 77.5% higher among people living in areas of high particulate matter exposure compared to people living in less exposed areas. Multivariable logistic regression analysis showed that age, gender, residential area, and family history of diabetes were significantly associated with the prevalence of diabetes (p<0.05). CONCLUSIONS: The present study indicates a link between high levels of exposure to PM2.5 and diabetes mellitus. Further prospective studies on populations exposed to elevated pollution are needed to establish whether this association has a causative link. PARTICIPANT CONSENT: Obtained. ETHICS APPROVAL: The study was approved by the Ethics Committee of the Prof. M Viswanathan Diabetes Research Centre, Chennai, India. COMPETING INTERESTS: The authors declare no competing financial interests.

Need for testing glucose tolerance in the early weeks of pregnancy.

AIMS: This observational study aims to determine the frequency of occurrence of glucose intolerance in the early weeks of pregnancy. MATERIALS AND METHODS: New World Health Organization 2013 guidelines recommends "A Single Step Procedure" (SSP) as an option for diagnosing gestational diabetes mellitus (GDM). Pregnant women attending 131 prenatal clinics across India for the first time underwent SSP consisting of administration of 75 goral glucose irrespective of the last meal timing and to diagnose GDM with 2 h plasma glucose (PG) value ≥7.8 mmol/L (7.8 mmol/L). RESULTS: In a cohort of n = 11,785, the number of pregnant women who underwent the test in first, second, and third trimesters were 4300, 4632, and 2853, respectively. Documented blood glucose values were available for 9282 pregnant women and in them, diagnosis of GDM was made in 740 (8%). Among them, 233 (31.5%), 320 (43.2%), and 187 (25.3%) were in the first, second and third trimesters, respectively. Positive family history of diabetes (43%) and history of fetal loss in previous pregnancy (27%) was more common in women diagnosed with GDM in the first trimester compared to GDM diagnosed in the second or third trimester. CONCLUSION: Manifestation of GDM in the early weeks of gestation is quite common.

Does effect of BCG vaccine decrease with time since vaccination and increase tuberculin skin test reaction?

The protective efficacy of BCG was studied for over 15 years, from 1968, in South India. A secondary analysis of data was performed to investigate the relationship between Bacille Calmette-Guérin (BCG) and tuberculosis (TB) disease and between BCG and positive tuberculin skin test for different time periods among children aged less than 10 years. A randomized controlled trial was conducted, where 281,161 persons were allocated to receive BCG 0.1mg, BCG 0.01mg or placebo. Tuberculin skin test was performed at baseline and at 4 years after BCG vaccination. Surveys were conducted every 2.5 years to detect all new cases of culture-positive/smear-positive TB occurring in the community over a 15-year period. Relative risk (RR) was obtained from the ratio of incidence among the vaccinated and the placebo groups. Among those children vaccinated with 0.1mg of BCG, the RR for TB was 0.56 (95% CI: 0.32-0.87, P=0.01) at 12.5 years but increased to 0.73 later. Similar pattern was seen with 0.01mg. The increase in the number of skin test positives with 0.1mg of BCG was 57.8%, 49.4% and 34% for cut-off points at ≥10mm, ≥12mm and ≥15mm, respectively. The study suggests that the effect of BCG may decrease since vaccination and the tuberculin positive was higher at post-vaccination test period due to BCG.

A cohort study of gestational diabetes mellitus and complimentary qualitative research: background, aims and design.

BACKGROUND: Women with gestational diabetes mellitus (GDM) and their offsprings are at increased risk of future type 2 diabetes and metabolic abnormalities. Early diagnosis and proper management of GDM, as well as, postpartum follow-up and preventive care is expected to reduce this risk. However, no large scale prospective studies have been done particularly from the developing world on this aspect. The objective of this study is to identify and follow a cohort of pregnant women with and without GDM and their offspring to identify determinants and risk factors for GDM, for various pregnancy outcomes, as well as, for the development of future diabetes and metabolic abnormalities. METHODS: This is a prospective cohort study involving pregnant women attending prenatal clinics from urban, semi-urban and rural areas in the greater Chennai region in South India. Around 9850 pregnant women will be screened for GDM. Socio-economic status, demographic data, obstetric history, delivery and birth outcomes, perinatal and postnatal complications, neonatal morbidity, maternal postpartum and offsprings follow-up data will be collected. Those diagnosed with GDM will initially be advised routine care. Those unable to reach glycaemic control with diet alone will be advised to take insulin. Postpartum screening for glucose abnormalities will be performed at months 3 and 6 and then every year for 10 years. The offsprings will be followed up every year for anthropometric measurements and growth velocity, as well as, plasma glucose, insulin and lipid profile. In addition, qualitative research will be carried out to identify barriers and facilitators for early GDM screening, treatment compliance and postpartum follow-up and testing, as well as, for continued adherence to lifestyle modifications. DISCUSSION: The study will demonstrate whether measures to improve diagnosis and care of GDM mothers followed by preventive postpartum care are possible in the routine care setting. It will also map out the barriers and facilitators for such initiatives and provide new evidence on the determinants and risk factors for both GDM development and occurrence of adverse pregnancy outcomes and development of future diabetes and metabolic abnormalities in the GDM mother and her offspring.

CRIS Guidelines (Checklist for Reporting In-vitro Studies): A concept note on the need for standardized guidelines for improving quality and transparency in reporting in-vitro studies in experimental dental research.

In vitro studies form a pivotal role in dental research contribution to a substantial evidence base. The reporting standards of these studies are not uniform thus resulting in lacunae in evidence reported. The effort of this concept note is to propose a Checklist for Reporting in vitro Studies (CRIS guidelines) that would promote quality and transparency in reporting in vitro studies.

Neonatal bacillus Calmette-Guerin vaccination and environmental mycobacteria in sensitizing antimycobacterial activity of macrophages.

An immunoepidemiological study was performed to evaluate the effect of neonatal bacillus Calmette-Guérin (BCG) vaccination and tuberculin response on macrophage killing profile against Mycobacterium tuberculosis. In this epidemiological field work, the study subjects were drawn from in and around Chennai city, South India. The descriptive epidemiological pattern of neonatal BCG vaccination and its impact on tuberculin skin test were studied. The study subjects for the immunologic laboratory experiments were recruited based on the skin test (Mantoux) outcome and were grouped in to 4 natural study groups that include vaccinated reactors, vaccinated nonreactors, nonvaccinated reactors and nonvaccinated nonreactors. In immunologic laboratory work part, the elucidation of macrophage killing profile was studied for all the 4 groups, and appropriate intercomparisons were made. The parameters used for the macrophage killing profile were (1) glutathione assay, (2) measurement of phagocytosis, (3) intracellular growth kinetics of M. tuberculosis H37Rv, (4) tumor necrosis factor-α assay and (5) interferon-γ assay. The results found that in the BCG-vaccinated tuberculin reactors the macrophage responses were significantly higher than the BCG-vaccinated tuberculin nonreactors. There was no significant difference in the responses among the BCG-vaccinated tuberculin reactors when compared with the nonvaccinated tuberculin reactors. The immune responses of nonvaccinated tuberculin reactors were significantly higher than the vaccinated tuberculin nonreactors. These findings show that the immune response among the adolescents/young adults is elicited by exposure to mycobacteria and not by the neonatal BCG vaccination.

Prevalence, severity and associated factors of dental caries in 3-6 year old children.

OBJECTIVES: To determine the prevalence and the severity of dental caries in 3-6 year old children in Chennai and to elucidate the factors which affect the dental caries in 3-6 year old children. METHODS: This study was a cross-sectional survey which was done on 527 children who were in the age group of 3 to 6 years, who were from 6 private and 6 corporation schools in Chennai, India. Two instruments were developed, pre-tested and validated for the study. One questionnaire which contained the various risk factors which had to be measured and the dental caries indices were used on children to collect the relevant data. A separate questionnaire was distributed to the parents to measure the socio economic status and to know the parents' educational levels. RESULTS: The prevalence of dental caries was found to be 63.4% in the study samples. The association between dental caries and the associated factors was determined by calculating the Odd`s ratio. Logistic regression was performed to test the magnitude of the association between dental caries and the factors which were associated with it, and linear regression was done for the continuous variables. There was a statistically significant high association between the oral hygiene practice, the eating habits of the children, the economic status and the parents' literacy levels and the caries prevalence in this study. CONCLUSION: This study showed that preventive efforts should be focused on young children, as the benefits are cumulative. The oral health promotion should particularly be targeted to the areas of need, to redress the inequalities.

Awareness and knowledge of common oral diseases among primary care physicians.

OBJECTIVE: The objectives of this study were to examine the level of awareness of the common oral disease amongst the primary care physicians in Chennai, India and to study the proportion of the routine oral examination among them. METHOD: This study was a cross-sectional, self administered, questionnaire survey which was done among 70 primary care physicians of Chennai, India. The questionnaire assessed the proportion of the routine oral examination and the knowledge and the awareness about the common dental problems among the primary care physicians. RESULT: This study showed moderate awareness about the signs and symptoms of the common oral diseases. There appeared to be a low awareness about the treatment of limited mouth opening and the causes of white patches. 85.9% of the doctors said that they routinely examined the oral cavity; 4.2% said that they sometimes did so. 4.2% of the sample said that they did not perform a routine oral examination, whilst another 4.2% said that they examined the throat only. CONCLUSION: The information which was gleaned from this study can help in developing a focused module which is aimed at the practising primary care physicians, and to suggest appropriate additions to the curriculum of the medical graduates, so as to enable an early detection, an appropriate referral, and an ultimately improved oral and general health of our population.

Associations of ß-cell function and insulin resistance with youth-onset type 2 diabetes and prediabetes among Asian Indians.

AIM: This study examined ß-cell function and insulin resistance (homeostasis model assessment-insulin resistance [HOMA-IR]) in Asian Indian youth with type 2 diabetes mellitus (T2DM-Y) and prediabetes. SUBJECTS AND METHODS: Eighty-two subjects with non-insulin-requiring type 2 diabetes and age of onset below 25 years were recruited within 18 months of diagnosis and compared with age- and sex-matched subjects with prediabetes (n=31) and normal glucose tolerance (NGT) (n = 83). Body mass index (BMI) and waist circumference were measured, and blood samples were taken in the fasting state and after 30, 60, 90, and 120 min of an oral glucose load for assessment of plasma glucose and insulin levels. Insulin sensitivity/resistance measures was calculated by using the reciprocal of the fasting insulin, the HOMA-IR equation, and the composite whole body insulin sensitivity index (Matsuda Index), and ß-cell function was calculated by the oral disposition index (DIo). RESULTS: T2DM-Y and prediabetes subjects had higher BMI, waist circumference, and fasting insulin than NGT subjects (P<0.05 for each). The 30-min insulin levels were lower in T2DM-Y and higher in prediabetes subjects compared with NGT (57 and 140 vs. 129 µIU/mL, P<0.001). The T2DM-Y group had greater insulin resistance (HOMA-IR, 1.87 vs. 0.97; P<0.05) and lower ß-cell function (DIo, 0.36 vs. 3.28; P<0.001) than NGT. In separate models, the Matsuda Index and DIo were independently associated with prediabetes and T2DM-Y (P<0.05). However, when both were included together, only DIo remained associated with T2DM-Y, whereas both DIo and Matsuda Index were associated with prediabetes (P<0.05). When controlled for adiposity (BMI and waist circumference), an association was observed but in opposite directions, with waist being positively associated with prediabetes (P = 0.016) and BMI negatively associated with T2DM-Y (P = 0.009). CONCLUSIONS: Among Asian Indians, ß-cell dysfunction appears to be more strongly associated with T2DM-Y than insulin resistance.

Clinical profile and complications of childhood- and adolescent-onset type 2 diabetes seen at a diabetes center in south India.

OBJECTIVE: This study describes the clinical characteristics of childhood- and adolescent-onset type 2 diabetes mellitus (CAT2DM) seen at a diabetes center in southern India. RESEARCH DESIGN AND METHODS: Between January 1992 and December 2009, 368 CAT2DM patients were registered. Anthropometric measurements were done using standardized techniques. Biochemical investigations included C-peptide measurements and glutamic acid decarboxylase antibody assay wherever feasible. Retinopathy was diagnosed by retinal photography; microalbuminuria, if urinary albumin excretion was between 30 and 299 mg/µg of creatinine; nephropathy, if urinary albumin excretion was ≥300 mg/µg; and neuropathy, if vibration perception threshold on biothesiometry was ≥20 V. RESULTS: The proportion of CAT2DM patients, expressed as percentage of total patients registered at our center, rose from 0.01% in 1992 to 0.35% in 2009 (P<0.001). Among the 368 cases of CAT2DM, 96 (26%) were diagnosed before the age of 15 years. The mean age at first visit and age at diagnosis of the CAT2DM subjects were 22.2±9.7 and 16.1±2.5 years, respectively. Using World Health Organization growth reference charts, 56% of boys and 50.4% of girls were >85(th) percentile of body mass index for age. Prevalence rates of retinopathy, microalbuminuria, nephropathy, and neuropathy were 26.7%, 14.7%, 8.4%, and 14.2%, respectively. Regression analysis revealed female gender, body mass index >85(th) percentile, parental history of diabetes, serum cholesterol, and blood pressure to be associated with earlier age at onset of CAT2DM. CONCLUSIONS: CAT2DM appears to be increasing in urban India, and the prevalence of microvascular complications is high. Female predominance is seen at younger ages.

Prevention of diabetes in rural India with a telemedicine intervention.

BACKGROUND: Diabetes care is not presently available, accessible, or affordable to people living in rural areas in developing countries, such as India. The Chunampet Rural Diabetes Prevention Project (CRDPP) was conceived with the aim of implementing comprehensive diabetes screening, prevention, and treatment using a combination of telemedicine and personalized care in rural India. METHODS: This project was undertaken in a cluster of 42 villages in and around the Chunampet village in the state of Tamil Nadu in southern India. A telemedicine van was used to screen for diabetes and its complications using retinal photography, Doppler imaging, biothesiometry, and electrocardiography using standardized techniques. A rural diabetes center was set up to provide basic diabetes care. RESULTS: Of the total 27,014 adult population living in 42 villages, 23,380 (86.5%) were screened for diabetes, of which 1138 (4.9%) had diabetes and 3410 (14.6%) had prediabetes. A total of 1001 diabetes subjects were screened for complications (response rate of 88.0%). Diabetic retinopathy was detected in 18.2%, neuropathy in 30.9%, microalbuminuria in 24.3%, peripheral vascular disease in 7.3%, and coronary artery disease in 10.8%. The mean hemoglobin A1c levels among the diabetes subjects in the whole community decreased from 9.3 ± 2.6% to 8.5 ± 2.4% within 1 year. Less than 5% of patients needed referral for further management to the tertiary diabetes hospital in Chennai. CONCLUSIONS: The Chunampet Rural Diabetes Prevention Project is a successful model for screening and for delivery of diabetes health care and prevention to underserved rural areas in developing countries such as India.

The Indian Council of Medical Research-India Diabetes (ICMR-INDIAB) study: methodological details.

BACKGROUND: Currently available estimates of diabetes prevalence in India are based on published data derived from very few studies. The Indian Council of Medical Research-India Diabetes (ICMR-INDIAB) study is a community-based survey conceived with the aim of obtaining the prevalence rates of diabetes in India as a whole, covering all 28 states, the National Capital Territory of Delhi, and two of the union territories in the mainland of India, with a total sample size of 124,000 individuals. METHODS: A stratified multistage sampling design has been used. In all study subjects, a structured questionnaire was administered and anthropometric parameters and blood pressure were measured. Fasting capillary blood glucose was first determined using a glucose meter. An oral glucose load was then administered to all subjects except those with self-reported diabetes, and the 2 h post-load capillary blood glucose was estimated. In every fifth subject, a fasting venous sample was collected for measurement of lipids and creatinine, a resting 12-lead electrocardiogram was performed, and dietary assessment questionnaire was administered. In all diabetic subjects, an additional diabetes questionnaire was used and a fasting venous sample drawn for glycated hemoglobin. RESULTS: All biological samples collected were analyzed in a central laboratory. All data collected were stored electronically. Quality control was achieved through multiple tiers of checks. CONCLUSIONS: The ICMR-INDIAB study is the first of its kind attempting to provide accurate and comprehensive state- and national-level data on diabetes prevalence in India.

Clinical profile of diabetes in the young seen between 1992 and 2009 at a specialist diabetes centre in south India.

AIM: To describe the trends and clinical profile of young diabetic patients (YD) attending a tertiary diabetes centre in south India. METHODS: We reviewed medical records of 2630 YD patients (age at onset ≤25 years) registered between 1992 and 2009. Patients were classified as type 1 diabetes (T1DM), type 2 diabetes (T2DM) gestational diabetes mellitus (GDM) and other types. Retinopathy was assessed initially by direct and indirect ophthalmoscopy and later by retinal photography, nephropathy if urine protein excretion was >500 mg/day, neuropathy if vibration perception threshold on biothesiometry was ≥20 V. RESULTS: The percentage of YD patients rose from 0.55% in 1992 to 2.5% in 2009 (trend chi square, 15.1, p<0.001). Of the 2630 YD subjects registered, 1135 (43.2%) had T1DM, 1262 (48.0%) had T2DM, 118 (4.5%) had GDM and 115 (4.4%) other types. T1DM patients were younger, had lower body mass index, waist circumference, systolic and diastolic blood pressures, and less family history of diabetes compared to T2DM (p<0.001 for each). Retinopathy was seen in 71.9% and 77.3% nephropathy in 22.1% and 12.1% and neuropathy in 34.5% and 21.4% of T2DM and T1DM respectively in those with ≥15 years duration of diabetes. CONCLUSIONS: The percentage of YD in south India is increasing, predominantly due to early onset T2DM.

Indian Diabetes Risk Score helps to distinguish type 2 from non-type 2 diabetes mellitus (GDRC-3).

AIM: The aim of this study was to investigate whether the Indian Diabetes Risk Score (IDRS) could assist in classifying type 2 diabetes mellitus (T2DM) and non-T2DM among patients attending clinics in India. METHODS: Patient records from 2006 through 2009 were taken from the clinical database of a tertiary care diabetes hospital in Chennai, Southern India. A total of 8747 patients with diabetes, diagnosed by a physician either as type 1 diabetes mellitus (T1DM), T2DM, or other types were included for analysis. The IDRS, based on age, abdominal obesity, family history of diabetes, and physical activity, was calculated for each patient at first visit to our clinic. Receiver operating characteristic (ROC) curves were generated to obtain optimal IDRS cut points for predicting T2DM and non-T2DM. RESULTS: Of the 8747 patient records analyzed, 204 (2.3%) were classified as non-T2DM and 8543 (97.7%) as T2DM. In ROC analysis, an IDRS ≥60 [area under the curve (AUC), 0.894; sensitivity, 83.8%; specificity, 81.0%] was predictive of T2DM, while an IDRS <60 (AUC, 0.882; sensitivity, 79.9%; specificity, 83.8%) was predictive of non-T2DM. CONCLUSIONS: The IDRS, a simple, cost-effective risk score, can assist in classifying T2DM versus non-T2DM among clinic patients in India.

Level of urbanization and noncommunicable disease risk factors in Tamil Nadu, India.

OBJECTIVE: To investigate the poorly understood relationship between the process of urbanization and noncommunicable diseases (NCDs) through the application of a quantitative measure of urbanicity. METHODS: We constructed a measure of the urban environment for seven areas using a seven-item scale based on data from the Census of India 2001 to develop an "urbanicity" scale. The scale was used in conjunction with data collected from 3705 participants in the World Health Organization's 2003 STEPwise risk factor surveillance survey in Tamil Nadu, India, to analyse the relationship between the urban environment and major NCD risk factors. Linear and logistic regression models were constructed examining the relationship between urbanicity and chronic disease risk. FINDINGS: Among men, urbanicity was positively associated with smoking (odds ratio: 3.54; 95% confidence interval, CI: 2.4-5.1), body mass index (OR: 7.32; 95% CI: 4.0-13.6), blood pressure (OR: 1.92; 95% CI: 1.4-2.7) and low physical activity (OR: 3.26; 95% CI: 2.5-4.3). Among women, urbanicity was positively associated with low physical activity (OR: 4.13; 95% CI: 3.0-5.7) and high body mass index (OR: 6.48; 95% CI: 4.6-9.2). In both sexes urbanicity was positively associated with the mean number of servings of fruit and vegetables consumed per day (P < 0.05). CONCLUSION: Urbanicity is associated with the prevalence of several NCD risk factors in Tamil Nadu, India.