PREVALENCE OF ISCHEMIC HEART DISEASE AMONG URBAN POPULATION OF SILIGURI, WEST BENGAL

Mandal S, Saha J B, Mandal S C, Bhattacharya R N, Chakraborthy M, Pal P P

Ind. J Comm. Med.34(1):19-23,2009

LEARNING OBJECTIVE-

To study the prevalence of IHD To study the causative risk factors associated with IHD

INTRODUCTION-

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

OBJECTIVE OF STUDY- To determine the prevalence of IHD and

associated risk factors among the urban population

METHODOLOGY- 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.

METHODOLOGY- 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 > 27Kg/m2 and overweight as BMI > 25Kg/m2

- Hypertension was diagnosed when SBP > 140 mmHg, and DBP > 90 mmHg, as per guidelines of British hypertension society.

- 12 lead ECGs were taken using BPL108 ECG machine on each individual and ECGs were reviewed with the cardiologist.

CRITERIA 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.

RESULTS- 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%)

TABLE 1: THE PREVALENCE OF IHD IN DIFFERENT AGE GROUPS AMONG STUDY

POPULATION

Age groups(years)

Study population

SymptomaticKnown + Rose

Questionnaire A

ECGFindings

B

TotalA+B

Odds Ratio

40-49 128(51.2) 4(3.1) 3(2.3) 7(5.4) 1

50-59 46(18.4) 3(6.5) 2(4.3) 5(10.8) 2.11

60-69 40(16.0) 3(7.5) 2(5.0) 5(12.5) 2.47

70-79 26(10.4) 4(15.35) 4(15.35) 8(30.7) 7.68

> 80 10(4.0) 2(20) 2(20) 4(40.0) 1.152

Total 250 16(6.4) 13(5.2) 29(11.6)

P value < 0.01

TABLE 2: DISTRIBUTION OF STUDY POPULATION ACCORDING TO CORONARY RISK FACTORS AND

PRESENCE OF IHDCoronary risk factors IHD + nt IHD - nt Total Fre%

ageOR P value

Smoking habit

Yes 18(20.45) 70(79.55) 88 35.2 3.53

No 11(6.7) 151(99.3) 162 64.8 1 o.oo12

Hypertension

Normal 3(3.3) 89(96.7) 92 1

High normal 3(7.5) 37(95.0) 40 52.8 2.41

Grade 1 hypertension 7(19.4) 29(80.6) 36 47.2 7.16

Grade 2 hypertension 10(21.8) 36(78.2) 46 8.24

Grade 3 hypertension 4(26.7) 11(73.3) 15 10.79

Isolated systolic Htn. (gr1) 1(7.1) 13(92.9) 14 2.28

Isolated systolic Htn. (gr2) 1(14.3) 6(85.7) 7 4.94 0.00008

TABLE 2: DISTRIBUTION OF STUDY POPULATION ACCORDING TO CORONARY RISK FACTORS AND

PRESENCE OF IHD

Coronary risk factors IHD + nt IHD - nt Total OR P value

BMI (Kg/m2 )

<18.5 4(9.1) 40(90.9) 44 1

18.5 – 23.5 7(6.8) 95(93.2) 102 0.74

23.5 – 25 5(11.9) 37(88.1) 42 1.35

25 – 30 8(19.05) 34(80.95) 42 2.35

> 30 5(25.0) 15(70.0) 20 3.33 0.03

TABLE 3: ASSOCIATION BETWEEN IHD AND CORONARY RISK FACTORS BY BINARY LOGISTIC REGRESSION ANALYSIS

Predictor Variable Standard Error P value

Age 0.021 0.378

Sex 0.585 0.660

BMI 0.032 0.468

Diastolic BP 0.025 0.003

Systolic BP 0.011 0.024

Smoking habit 0.621 0.025

Diet 0.957 0.597

Physical activity 0.227 0.713

DISCUSSION-

Author Study Years

Region Residence

Prevalence rate (%)

Present study 2005 Siliguri, Urban 11.6%

Latheef, et al 2006 Tirupati Urban 12.63%

Gupta et al 2002 Jaipur Urban 8.2%

Mohan et al 2001 Chennai Urban 11%

ICMR study 1989-1994

Delhi Urban and Rural

U-7.6% R- 1.5%

ICMR study 1989-1994

Vellore Urban and Rural

U- 4.0%R- 1.5%

Mathur K S 1960 Agra Urban 1.05%

Jajoo UN 1988 Vidarbha Rural 1.69%

TABLE 4: COMPARATIVE ANALYSIS BETWEEN STUDIES WITH REGARD TO REPORTED PREVALENCE OF CHD

CONCLUSION-

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.

CRITICAL 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.