P REVALENCE OF I SCHEMIC H EART D ISEASE A MONG U RBAN P OPULATION OF S ILIGURI, W EST B ENGAL Mandal S, Saha J B, Mandal S C, Bhattacharya R N, Chakraborthy M, Pal P P

L EARNING O BJECTIVE - To study the prevalence of IHD To study the causative risk factors associated with IHD

I NTRODUCTION - Cardiovascular disease has become a major public health problem in many developing countries. About two-thirds of the global estimated 14.3 million annual cardiovascular disease deaths occur in the developing world. By the year 2015, cardiovascular diseases could be the most important cause of mortality in India. The prevalence of coronary artery disease in India increased from 1% in 1960 to 9.7% in 1995 in urban populations, and in rural populations it has almost doubled in the last decade

O BJECTIVE O F S TUDY - To determine the prevalence of IHD and associated risk factors among the urban population

M ETHODOLOGY - Study Design- Cross sectional study Study Setting- Study area - Population from the Municipal Corporation area of Siliguri was included in the study. - Out of 47 wards in Siliguri Municipal corporation area, ward no.23 (Dabgram) and 47 (Pati colony) were selected for the study. Sample Size - The sample size of 246 was calculated using expected prevalence of IHD among urban population in India as 9.7%, worst acceptable prevalence as 6% and confidence level of 95%. - Considering a non-response of 10%, a sample size of 271 individuals was decided. Study subjects -From the updated voter list of 2 wards, all members who were permanent residents aged >40 yrs old were selected. - By using systematic random sampling method, a list of 271 members aged > 40 yrs with name & address was prepared.

M ETHODOLOGY - Data collection- - Necessary data was collected after obtaining informed consent - A pre-tested, semi-structured questionnaire was used for data collection (modifications to Rose questionnaire) - the smoking habit was stratified according to number of cigarettes smoked per day and the duration of smoking -Physical activity was categorized as sedentary lifestyle if a person walked less than 14.5 km a week. - BMI was calculated and obesity defined as BMI > 27 Kg/m 2 and overweight as BMI > 25 Kg/m 2 - Hypertension was diagnosed when SBP > 140 mmHg, and DBP > 90 mmHg, as per guidelines of British hypertension society. - Hypertension was diagnosed when SBP > 140 mmHg, and DBP > 90 mmHg, as per guidelines of British hypertension society lead ECGs were taken using BPL108 ECG machine on each individual and ECGs were reviewed with the cardiologist lead ECGs were taken using BPL108 ECG machine on each individual and ECGs were reviewed with the cardiologist.

C RITERIA FOR DIAGNOSIS OF IHD History of angina or infarction and previously diagnosed disease An affirmative response to the Rose questionnaire ECG findings namely Minnesota codes 1-1, 4-1, 5-9, 5-2 or 9-2. The presence of all three criteria were taken as the confirmation of the diagnosis of ischemic heart disease. DATA ANALYSIS: Data was entered in EPIINFO software, version 3.2 and then exported to SPSS version 10 for analysis. Association between the prevalence of IHD and risk factors were examined.

R ESULTS - Of the 271 individuals > 40 years enrolled in the study, 250 took part in the study. 29 (11.6%) among them had IHD. The prevalence was higher among males (13.5%) as compared with females (9.4%)

T ABLE 1: T HE PREVALENCE OF IHD IN DIFFERENT AGE GROUPS AMONG STUDY POPULATION Age groups (years) Study population Symptomatic Known + Rose Questionnaire A ECG Findings B Total A+B Odds Ratio (51.2)4(3.1)3(2.3)7(5.4) (18.4)3(6.5)2(4.3)5(10.8) (16.0)3(7.5)2(5.0)5(12.5) (10.4)4(15.35) 8(30.7)7.68 > 8010(4.0)2(20) 4(40.0)1.152 Total25016(6.4)13(5.2)29(11.6) P value < 0.01

T ABLE 2: D ISTRIBUTION OF STUDY POPULATION ACCORDING TO CORONARY RISK FACTORS AND PRESENCE OF IHD Coronary risk factorsIHD + ntIHD - ntTotalFre% age ORP value Smoking habit Yes18(20.45)70(79.55) No11(6.7)151(99.3) o.oo12 Hypertension Normal3(3.3)89(96.7)921 High normal3(7.5)37(95.0) Grade 1 hypertension7(19.4)29(80.6) Grade 2 hypertension10(21.8)36(78.2) Grade 3 hypertension4(26.7)11(73.3) Isolated systolic Htn. (gr1)1(7.1)13(92.9) Isolated systolic Htn. (gr2)1(14.3)6(85.7)

T ABLE 2: D ISTRIBUTION OF STUDY POPULATION ACCORDING TO CORONARY RISK FACTORS AND PRESENCE OF IHD Coronary risk factorsIHD + ntIHD - ntTotalORP value BMI (Kg/m 2 ) <18.54(9.1)40(90.9) – 23.57(6.8)95(93.2) – 255(11.9)37(88.1) – 308(19.05)34(80.95) > 305(25.0)15(70.0)

T ABLE 3: A SSOCIATION BETWEEN IHD AND CORONARY RISK FACTORS BY BINARY LOGISTIC REGRESSION ANALYSIS Predictor VariableStandard ErrorP value Age Sex BMI Diastolic BP Systolic BP Smoking habit Diet Physical activity

D ISCUSSION - AuthorStudy Years RegionResidencePrevalence rate (%) Present study2005Siliguri,Urban11.6% Latheef, et al2006TirupatiUrban12.63% Gupta et al2002JaipurUrban8.2% Mohan et al2001ChennaiUrban11% ICMR study DelhiUrban and Rural U-7.6% R- 1.5% ICMR study VelloreUrban and Rural U- 4.0% R- 1.5% Mathur K S1960Agra Urban 1.05% Jajoo UN1988Vidarbha Rural 1.69% TABLE 4: COMPARATIVE ANALYSIS BETWEEN STUDIES WITH REGARD TO REPORTED PREVALENCE OF CHD

C ONCLUSION - The prevalence of coronary artery disease and coronary risk factors is high in urban population in India. Further research is required to document the impact of lifestyle modification and controlling the stated risk factors.

C RITICAL COMMENTS - Strengths- An updated voter list is used to select study subjects by systematic random sampling Standard questionnaire(Rose Questionnaire) and standard Classification for BMI for SEAR are used Limitations- Physical activity is not assessed correctly Factors like Smoking, Physical activity are not adequately analyzed Known coronary risk factors like Diabetes and lipid profile were not included in the study OR for risk factor variables is not mentioned in logistic regression analysis.