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Indian Journal of Community Medicine

Prevalence of Hypertension Amongst the Employees of a Mega-Industry of South Gujurat

Author(s): Pradeep Kumar, Vikas K. Desai, JK Kosambia

Vol. 27, No. 1 (2002-01 - 2002-03)

Deptt. of P.S.M., Government Medical College, Surat (India) 395 001


Research question: What is the prevalence of hypertension in the employees of a mega industry?

Objective: To find out the prevalence of hypertension and the impact of various risk factors on it and suggest the remedial measures.

Study design: Population based cross-sectional study during 1994-95.

Settings: A mega industry located in South Gujarat.

Participants: 1300 employees of the industry.

Results: Coverage rate of study population was only 76%. The prevalence of hypertension was high (24%). Hypertension was more in general shift workers and in certain sections (transport, finance and accounts, fire brigade, security etc.). Prevalence was also high in persons who were overweight or consuming alcohol and/or tobacco. Treatment compliance amongst 204 "aware" patients was only 17%.

Keywords: Prevalence of hypertension, Industrial workers, Risk factors


Hypertension a disease in itself is also an important risk factor for coronary artery disease (CAD). Blood pressure is the single most useful test for identifying individuals at a high risk of CAD1. The incidence and consequent prevalence of hypertension in our country are showing rapid increase in certain populations (adult urbanites from upper/middle social class). Past studies reported the prevalence of hypertension in adults between 3-6 percent 2 and little higher in urban population (14.6%) 3. Recent studies put this figure even in youngsters as high as 27 percent 4. This high morbidity and mortality (mainly due to the CAD) have generated awareness in population as well as treatment providers. Working in organized large-scale industry offers a comfortable and financially attractive life. At the same time it also brings in certain life style changes, which do result in the increased incidence of various non-communicable diseases including hypertension. We received a letter from the medical officer in charge of a mega industry of South Gujarat apprehending an epidemic of hypertension in the industry. the letter also contained a list of 145 employees suffering from various grades of hypertension. The Medical Officer asked us to suggest some remedial measures. He also wanted to be sure that this high incidence of hypertension is not an isolated phenomenon restricted to his industry. A meeting was held with the management of industry and it was decided to find out the true prevalence of disease in the employees before suggesting any measures. Accordingly this study was planned.

Material and Methods:

All employees were covered during working hours at their work-place. Methods used were interview, clinical examination, recording of blood pressure, height and weight.

Survey team comprised of faculty from medical college and paramedical staff from the health facility of the industry. Information was entered on a pre tested proforma. Participation in the study was voluntary, however, special/repeat visits were made to improve the coverage.

Measurement of blood pressure: It was done by mercury sphygmomanometer. Instruments were of the same batch and calibrated from time to time. Two readings in lying down posture at 10-15 minutes interval were taken and only second reading (being lower and more realistic) was considered.

Other measurements: Height (in full centimeters) and weight (nearest to 100 grams) were recorded in standard clothing, without shoes by using standard instruments.

Diagnostic Criteria: Based on the criteria of JNC VI 5 , a person was considered as suffering from hypertension if -Systolic blood pressure (SBP) was 140 mm of mercury or above and/or diastolic blood pressure (DBP) 90 mm of mercury and above or -Is already on anti hypertensive treatment.

Statistical analysis: Prevalence of hypertension was calculated for the population and its subgroups based on the presence/absence of risk factors. Confidence intervals for the prevalence at 95 percent level of significance were calculated 6 . All individuals suffering from hypertension were referred to the health facility for detailed check-up and institution of treatment. They were informed about the preventive measures, non-pharmacological management and regular medication.

Results: The industry under study, Krishak Bharti Co-operative Limited (KRIBHCO) was incorporated in 1980. Its plant is located at Hazira near Surat. This plant had a work force of 1300. It uses natural gas as raw material and its main products are urea and ammonia. Since 1995, it has also started producing bio-fertilizers.

Out of 1300 employees, 990(76%) employees including 5 females participated in the study. Further observations are in relation to 985 males whose age varied between 20-59 years.

Table I: Distribution of blood pressure according to age.

Age (year) No. Examined Blood pressure (mm of mercury)
Systolic Mean ±SD Diastolic Mean ±SD
20-29 104 129.7±13.1 81.9±7.4
30-39 493 129.0±13.7 84.3±8.3
40-49 291 129.2±13.9 85.4±9.8
50-59 62 136.8±17.0 86.1±0.2

Persons who did not state their age (n=35) were excluded.

Distribution of mean values of SBP and DBP in relation of age revealed a weak relationship upto 49 years of age. The mean SBP was around 129 mm while the mean DBP increased from 82 mm (20-29 years) to 85 mm (40-49 years). Both SBP and DBP showed a sharp increase in 50-59 years of age. Variability in both SBP and DBP (reflected by standard deviation) was also maximum in the same age.

Table II: Prevalence of hypertension according to age.

Age (year) No. Examined Hypertension No. (%) Confidence interval (95%)
20-29 104 11 (10.5) 5.2-18.8
30-39 493 106 (21.5) 17.9-25.8
40-49 291 86 (29.6) 24.7-35.5
50-59 623 24 (38.7) 24.8-57.6
Not stated 5 10 (28.6) 13.7-52.6
Total 985 237 (24.1) 21.2-27.4

Age not stated (35) were excluded for application of test of significance. x 2 = 24.38, df=3, p=.00002.

Prevalence of hypertension increased significantly with the increase in age and was very high (38.7%) in 50-59 years age. The overall prevalence of hypertension in the study was 24.1 percent.

Table III: Prevalence of hypertension according to type of duty (n=985).

Type of duty No. Examined Hypertension No. (%) Confidence interval (95%)
Rotatory 402 55 (13.7) 10.5-17.8
Regular 296 84 (28.4) 22.9-35.2
General 189 79 (41.8) 33.6-52.1
General/shift 45 5 (11.1) 3.6-25.6
Not stated 53 14 (26.4) 13.2-47.2

Not stated (53) excluded for application of test of significance. X2 = 63.63, df=3; p=0.00000.

When viewed in relation to various shift duties, prevalence of hypertension was high (41.8%) in general shift workers than the workers from all other shifts. This difference was found to be statistically significant.

Table IV: Prevalence of hypertension according to the department of working (n=985).

Department No. examined Hypertension Confidence interval
No. (%)
Human resources development (HRD) 68 23 (33.8) 21.4-50.7
HRD Project/designing (computer cell) 12 2 (16.6) 2.0-60.0
Technical 356 69 (19.4) 15.3-24.6
Commercial 68 20 (29.4) 18.0-45.4
Maintenance 13 3 (23.1) 4.8-67.5
Production 264 42 (15.9) 11.8-21.5
Finance & accounts 62 32 (51.6) 36.5-73.0
Medical 7 1 (14.3) 0.4-79.7
Transport 31 14 (45.2) 24.7-75.9
Security/Free brigade 104 3 (29.8) 21.0-42.4

Prevalence of hypertension in different departments was studied and it was very high in Finance and Account (51.6%) and transport (45.2%). It was also high amongst security and fire brigade persons (29.8%). No statistical test could be applied for testing the significance of the difference because of multiple groups, small frequencies and the diverse nature of sub-groups which did not allow any clubbing of adjacent groups.

Table V: Prevalence (%) of hypertension amongst employees according to their age and duration of employment.

Age (years) Duration of employment at KRIBHCO (years) Total
≤ 5 6-10 ≥ 11
20-29 59 (11.9) 35 (8.6) 10 (10.0) 104 (10.6)
30-39 41 (31.7) 273 (17.2) 157 (25.5) 471 (21.2)
40-49 42 (28.6) 104 (30.8) 103 (29.2) 276 (29.7)
50-59 4 (25.0) 13 (53.8) 37 (32.4) 54 (37.0)

Persons who did not state age or duration of work or both were (80) excluded. Figures in parentheses indicate prevalence of hypertension X 2 = 4.21, df=2, p=.12157.

Attempt was made to find out the relationship between hypertension and duration of employment in this industry. The prevalence was high in persons with long duration of working at KRIBHCO (≥11 years), though this difference was not significant. Further this difference was an effect of age and became apparent when the prevalence rates of hypertension were seen separately in persons with varying durations of working in different age groups.

Out of the persons who did not state their age (29), or duration of working (45) or both (6)24 were suffering from hypertension (prevalence rate = 30%).

Table VI: Prevalence of hypertension according to the grade of obesity (BMI).

Body mass index (BMI) Total examined Hypertension No. (%) Confidence interval (95%)
≥30 (gross obese) 77 27 (35.1) 23.1-51.0
25-29.9 (over weight) 366 118 (32.1) 26.9-38.6
20-24.9 (normal) ≤ 421 83 (19.7) 15.9-24.4
19.9(under weight) 98 6 (6.1) 2.2-13.3
Not done 23 3 (13.1) 2.7-38.3

X 2 = 39.78, df=3, p=.00001.

Interrelationship between the prevalence of hypertension and the obesity was studied. The prevalence of over weight/obesity (BMI ≥ 25) was 45%. Prevalence of hypertension was also high in obese (35.1%) and over weight (32.2%) persons than others and this difference was statistically significant.

Table VII: Prevalence of hypertension according to the various habit(s) (n=985)

Habit(s) Total examined Hypertension No. (%) Confidence interval (95%)
Yes 127 47 (37.1) 27.8-49.4
No 858 190 (22.1) 19.2-25.4
Tobacco intake (Smoking/chewing)
Yes 223 66 (29.6) 23.3-37.7
No 762 171 (22.4) 19.3-26.6
Physical exercise
Yes 187 45 (24.1) 18.0-32.3
-Regular 235 53 (22.5) 17.2-29.5
-Occasional 563 139 (24.7) 20.9-29.2

Not stated (23) excluded for test of significance. X 2 = 39.78, df=3, p=.00001.

Based on the history of intake of alcohol and tobacco, prevalence rates of hypertension were significantly high in persons consuming alcohol (37.0%) and/or tobacco (29.6%). However, with relation of physical exercise, the prevalence was almost same (22.5%-24.7%) in the persons who were doing/not doing any physical exercise. As expected these differences were statistically not significant.

Social class: No classification was used to grade the employees in different social classes, but looking to the working conditions, educational backgrounds and pay structure almost all of them seemed to belong to upper/upper middle or middle social class.

Work place environment: A visit to various parts of industry did not reveal any physical/chemical factor, which can be implicated in causation of hypertension.

Treatment compliance: In this study, 237 persons were detected as having hypertension, needing drug-based management, 204 were already aware about their disease but only 35 of them were taking regular treatment.


Coverage rate of 76% was unsatisfactory for following reasons:

  • It was a door-step survey at the work place of the employees.
  • Several visits with prior information were made to ensure the coverage.
  • Participants were educated and supposedly health conscious,
  • Disease carries no stigma - no reason for deliberate non participation.

Participation was poorer in the medical section affecting the participation from other sections as well. Persons from this section should set an example by participation thus motivating others. Poor participation stresses the need to generate awareness about the hypertension, its early detection through such surveys and timely management.

Overall prevalence of hypertension in the study was 24.1%. It is high when compared with the adults of our country from rural (3-4%) and urban (5-7%) areas in the studies done 20-22 years ago 2 . A study in 1986 from the same region in urban adult males found the prevalence of hypertension as 14.6% 3 . A recent study from Delhi amongst adults (30-39 years) found the prevalence of only 5.2% 7 . Our findings, however, compare well with 27% prevalence of hypertension amongst younger doctors (mean age 24.8± 3.4 years) from Delhi in 2000 4.

Decreased physical activities coupled with increased mental stress (job related/other-wise) are determinants of hypertension. High prevalence of hypertension is, therefore, reported from the industries where working is mostly automatic and mechanised. The industry under study fitted in this picture. Very high prevalence in higher age group of 50-59 years is otherwise also well documented 8 and is attributed to the accumulated effect of various risk factors. A study from same area also amongst industrial workers revealed high prevalence of hypertension based on systolic (17%) or diastolic (29%) blood pressure or any one of them (31%) 9 . Contrary to the expectations, prevalence of hypertension was high in workers from day duty. It had nothing to do with the duty timings but due to the fact that most of these people were from the office of general administration and not from the production or maintenance. These people may have to face additional mental stress-yet another determinant of hypertension.

Physical and mental stresses vary in different work sections and hence the environment at work place is an important determinant for hypertension. High prevalence in the sections of transport, security and fire brigade can be explained because of sedentary working and changed life style. Most of these persons are the ex-servicemen who usually stop the exercises etc. but continue with their alcohol intake. More hypertension in F&A section can be due to the job related stress. One of the participant jokingly said, "These guys are supposed to give tension to every body else but in the process they seem to get hypertension". Working at such places should be investigated to find out the reasons for the high prevalence. Low prevalence from production, maintenance and technical sections support the view that there is nothing in the process of production or maintenance at plant site, which can be implicated in the causation of hypertension.

Obesity depends on the increasing age, lack of physical activity, sedentary job and diet rich in fat and cholesterol. Taking BMI of 25 and above as cut off point, 45% of employees were either over weight or obese. This figure was high even when compared with similar population from other studies 9. Prevalence of hypertension was high in obsese population in comparison to the people who were weighing normal or under weight. Obesity was 17% in the younger medicos of Delhi and the prevalence of hypertension in this group was 27 percent 4. In yet another study BMI strongly correlated with blood pressure across and within the population 8.

Attempts were made to relate the prevalence of hypertension, with the known determinants (alcohol and tobacco). 13% workers reported alcohol intake. It is less than 29% reported elsewhere in comparable population 9. In view of prohibition on alcohol consumption in the state, this information is not reliable otherwise also it always reflects under reporting. Tobacco consumption in this study (22.6%) compares well with the smoker rate (29%) in similar population 9. High proportion of people consuming alcohol and/or tobacco and further higher prevalence in the persons taking these substances emphasize the need to highlight their role and accordingly people may be advised to remain away or give up the use of these substances. Higher prevalence of hypertension in those who smoke or take alcohol has also been reported elsewhere 4,9. In view of this it seems dubious to encourage alcohol use for the purpose of reducing risk of CAD 8.

Regular physical exercise reduces hypertension (need of drugs) and is advocated for prevention/management of the hypertension. However, present study reported similar prevalence of hypertension amongst employees irrespective of the fact whether they are exercising or not. This finding was unusual and could be due to the following facts:

  • Information about the exercise was subjective, relied up on the employees.
  • Many employees started exercise after the detection of hypertension on the advice of physician and so its role in preventing the hypertension could not be established.

Untreated/inadequately treated patients are at equal risk of hypertension related complications. We came across several aware patients with DBP between 120-140 mm of mercury and were still not taking any treatment. They were only "ticking time bombs which were moving freely". Poor treatment compliance by such cases in alarming and is essential to be targeted through intervention.


  • Coverage was poor though all the participants were educated and from upper/middle class.
  • Prevalence was high and was more so in aged, obese persons working in day shift, in F&A, transport, security and fire brigade and who were consuming alcohol and/or tobacco.
  • Treatment compliance was poor though the participants were educated and the best facilities for treatment were available free of cost.


Population based strategy (To all): An awareness program be started for employees and dependents through print, cable network and direct group meetings. The medical persons of the industry must do this with the help from the professionals from outside for IEC. It should focus on simple questions such as

  • What is hypertension?
  • What are its signs and symptoms?
  • What are the dangers if it remains undetected/untreated?

Additionally the IEC should cover the risk factors which may be present at the residence/work place or related with the life style, various risk reduction strategies and the need of periodic monitoring of blood pressure.

Active case detection is crucial and should be done by periodic health check-up of employees and their family members (also a high risk group). Efforts should be made to encourage the participation by informing that such check-up of apparently healthy persons are important and by this most of asymptomatic hypertensive patients are detected. Blood pressure must be recorded at least once in three months in general population and at least once in a month in those suffering from any grade of hypertension. In fact in such set up, there is no need for a special campaign to detect the hypertension but it should be integrated with the regular health check-up.

High risk group strategy (To hypertensives): IEC messages for all the hypertensive patients (known, potential, borderline etc.) must include the additional information about risk reduction methods, need to take regular and supervised treatment and monitoring of blood pressure (all this even when they feel apparently healthy).

  • Looking to the high disease load, a full time physician with postgraduate qualification can be recruited for curative and rehabilitative services. He will also be useful in organizing the preventive care.
  • Health center must upgrade its emergency care facilities to attend to the patients round the clock with complications of hypertension or of associated diseases (stroke, coronary heart disease etc.)

It also emphasizes the need for similar studies in other industries having similar environment as the reports9 from other industries also indicate an increase in cases of hypertension in recent time.

A high non-participation (24%) requires cautious interpretation of the findings of the study.


Authors acknowledge the contribution of authorities at the industry in granting the permission and extending the co-operation for conduction of this study.


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