The American Heart Association Classiﬁcation of Blood Pressure and the Determinants of Hypertension among Medical Practitioners in Bayelsa State: A Cross-Sectional Study

Hypertension is a major risk factor for cardiovascular diseases (CVD). Objective was to assess prevalence of hypertension using 2017 American Heart Association/American College of Cardiology (AHA/ACC) guideline and it's determinants among Medical Practitioners in Bayelsa State, Nigeria. Two hundred and forty-four apparently healthy medical doctors were recruited. A structured self-administered questionnaire was used to gather data on CVD risk factors. Anthropometric and blood pressure measurements were taken. Association between hypertension and sociodemographic features, anthropometric measures, smoking, alcohol, fruit and salt intake, exercise was explored with chi-square for proportions. Predictors of hypertension were identiﬁed by two-step binary logistic regression. A third of participants were women (29.9%), most were below age 30 years (40.2%) and married (54.9%). One ﬁfth was consultant/professor cadre (18.9%) and a third had worked ≥11 years as medical practitioners. Almost 2 in every 3 of the participants (63.1%) were considered hypertensive by the AHA 2017 classiﬁcation. However, using a cut oﬀ of ≥140/90mmHg used by other guidelines gave a prevalence of 25%. Only 13.5% had been diagnosed hypertensive prior to this study. The most important predictor of occurrence of hypertension was age, although marital status, salt intake, work cadre and duration of practice were also signiﬁcantly associated with the occurrence of hypertension. The use of the 2017 ACC/AHA hypertension guidelines for diagnosis of hypertension with a blood pressure cut oﬀ ≥ 130/80 mmHg resulted in a marked increase in the prevalence of hypertension in medical doctors compared to other guidelines that use a cut oﬀ value of 140/90mmHg (63.1% versus 25%). Increasing age is a signiﬁcant predictor of hypertension in medical doctors. Guidelines that are best suited for our local settings for diagnosis of hypertension are recommended.

diastolic blood pressure of 80 mm Hg or more in contrast to other guidelines which have used systolic blood pressure of 140 mm Hg or more and or a diastolic blood pressure of 90 mm Hg or more to define [2][3][4][5][6] hypertension. It further recommends that high risk patients with stage 1 hypertension (BP between 130/80 to <140/90 mmHg), with ASVD risk score of greater than 10% or cardiovascular disease (CVD), should be 1 considered for drug treatment. However, both the recent European and the 2017 American guidelines recommend the same therapeutic BP goal of <130/80 1,3,4 mm Hg. There is strong evidence that intensive BP lowering is highly beneficial in lowering the risk of major CV events with markedly significant reductions in the risks of coronary heart disease, stroke, heart failure 7 and all-cause mortality. Lee et al. using the National Health Insurance Service Health Examination Database of Korea for 2005-2006, analyzed 148,761 low risk, treated stage 1 hypertensive subjects (systolic BP of 140 to 159 mm Hg or diastolic BP of 90 to 99 mm Hg). They found that the lowest adjusted risk of all-cause mortality was observed in subjects with an average SBP of 120 to <130mmHg and an average 8 DBP of 70 to <80mmHg. These findings support the generalization of the recommended target BP of <130/80mmHg of the latest ACC/AHA and ESH/ESC 1,3 guidelines in the general hypertensive population. Systemic hypertension leads globally among causes of cardiovascular mortality and morbidity despite its easy diagnosis and availability of treatment options (pharmacologic and non-pharmacologic). Uncontrolled hypertension promotes target organ damage (eyes, brain, heart, kidneys, coronary and peripheral vessels) and confers a significant disease burden to the community. Prevalence of hypertension in Nigeria is estimated at 9,10 30.6% and 26.4% among urban and rural dwellers, 11 respectively in a population of over 170 million with 48% of this large population residing in cities while the 12 remaining 52% reside in rural areas. The prevalence of hypertension in Nigeria may form a substantial proportion of the total burden of hypertension in Africa because Nigeria is the most [9][10][11][12] populous and the most populated country in Africa. Several studies in Nigeria have shown a high prevalence of hypertension in medical doctors, similar 13,14 to levels found in the general population. But these studies used a cut off value of ≥140/90mmHg which is 2,3,5,6 the recommendation of several guidelines.
Medical doctors are a selected group of adult population often missing in the literature, as the focus of most studies is on the general population or patients presenting to health facilities. The present study assessed the prevalence of hypertension using the 2017 AHA/ACC guideline and determinants of hypertension among Medical Practitioners in Bayelsa State, Nigeria.

Study setting
The study held in Bayelsa state, Nigeria. Bayelsa state is one of the six states in the Niger Delta region, created in the year 1996 from Rivers State, in the southsouthern region of Nigeria. It is bounded by Delta state on the north, Rivers state on the east and the Atlantic Ocean on the western and southern parts. There are 8 local government areas in the state of which Yenagoa local government area (LGA) accommodates the state's administrative headquarters. It is the traditional home of the Ijaw people with an approximated total population of 1,703, 984 (projected from the 2006 census) and an annual growth rate of 3%. The Primary Health Care Board, State Ministry of Health, and Hospitals Management Board manage the healthcare system in the state. The healthcare service delivery system is organized along three levels of careprimary, secondary, and tertiary in the private and public sectors. The primary level is made up of a network of primary healthcare (PHC) centres with at least 1 PHC in 105 local administrative wards of the state. There are least 2 general hospitals in each of the 8 LGAs of the state which make up the secondary level of care. The state has 2 tertiary health facilities -the Federal Medical Centre, Yenagoa and the Niger Delta University Teaching Hospital, Okolobiri -that serve as referral centres for the network of general hospitals and primary health centres distributed across the state and hospitals in neighboring states such as Delta, Rivers, 15,16 Akwa-Ibom, Edo, and Imo in Nigeria. There is a maldistribution of medical doctors across the different levels of care with a very high concentration of doctors in the tertiary centres to the detriment of the other levels of 17 care.

Study population
Two hundred and forty-four apparently healthy medical doctors were recruited. There are about seven hundred medical doctors registered to practice in the three levels of healthcare service delivery in both public and private health sectors of Bayelsa state. Participants included house officers, resident doctors, medical officers, consultants and professors in various specialties and sub-specialties of medical practice. The study excluded visibly pregnant female medical doctors.

Study procedures Questionnaire
The study used a self-administered questionnaire developed using the WHO STEP wise (2018) approach 19 to surveillance guidelines which has been used in studies of total cardiovascular risk in several 20 populations . This was used to gather information on selected demographic characteristics including gender, age, number of years of medical practice and staff cadre, dietary intake, physical activity, tobacco and alcohol use, systolic and diastolic blood pressures

Physical examination
This included measurements of height and weight (to determine the body mass index), waist circumference, pulse rate, blood pressure, and collection of blood samples for random blood sugar using standard 5,[19][20][21][22][23] protocols. . Height was measured in meters using a standardized stadiometer with each participant standing feet together without shoes on. They stood upright on the scale, not leaning on any support/ wall with their heads up before the readings were taken. Weight was measured in kilograms with the participants wearing light clothing. Each participant removed everything in their pockets such as phones and keys, dropped their handbags, and were relieved of any material that could have increased their weight temporarily. Also, it was ensured that the weight scale was on the zero mark before each participant climbed on it for the measurement. A standardized weight scale was used. Body mass index was calculated as weight in kg divided by the square of 2 the height in meters (kg/m ). Obesity was defined as a 2 BMI of ≥30 kg/m using the WHO categorization. A BMI of <18.5, 18.5-24.9, and 25-29.9 kg/m2 was characterized as underweight, normal, and overweight, 1 9 , 2 4 respectively.
Measurement for the waist circumference (WC) (to the nearest 0.1cm) was done using a non-stretch linear tape, which was placed at the approximate midpoint between the lower margin of the last palpable rib and the top of the iliac crest. A WC cutoff of 94 cm for European men and 80 cm for European women was regarded as elevated and 21 indicative of abdominal obesity. Random blood glucose levels were determined before participant's lunch using Accucheck glucometers. Diabetes mellitus and impaired glucose tolerance were defined by random blood glucose of ≥11.1 and ≥7.8 mmol/L, respectively or if there was a prior diagnosis of DM with use of insulin or oral hypoglycemic drugs at the time of survey. The measurements were taken by either the principal investigator or 3 well-trained house officers and a resident doctor. Systolic blood pressure w a s m e a s u r e d u s i n g a n A c c o s o n m e r c u r y s p h y g m o m a n o m e t e r w i t h t h e m e a n o f t w o measurements taken in rested participants in sitting 5 position. Blood pressure was measured at the same time of the day (by 9am). Participants were instructed to avoid alcohol consumption, cigarette smoking, coffee/tea, and exercise for at least 30 minutes prior to these measurements. All participants provided written informed consent and the study was approved by the Ethics Committee of the Niger Delta University Teaching Hospital (NDUTH), Okolobiri, Bayelsa State in line with the Helsinki Declaration of 1975 that was revised in 2000. (Ethical Clearance certificate no. NDUTH REC/0039b/2017, th approved 6 July 2018)

Data Analysis
Collected responses were checked and fed into an excel sheet on a personal computer. Data analysis was done after data cleaning and completeness were ascertained. A n a l y s e s w e r e d o n e t o d e t e r m i n e t h e sociodemographic characteristics and hypertensive status of medical practitioner in the study. Participants were classified as hypertensive with a systolic blood pressure reading of ≥ 130mmHg and/or diastolic blood pressure of ≥ 80 mmHg according to the 2017 AHA/ACA classification. Participants receiving antihypertensive medications were also classified as hypertensive. Data was presented as frequency distribution tables and descriptive statistics like means, standard deviation were calculated. Association between hypertension (dependent variable) and explanatory variables like sociodemographic features, anthropometric measures, smoking, alcohol, fruit and salt intake, exercise was explored with Chi-square for proportions. Predictors of Hypertension were identified by a two-step binary logistic regression. In the first step of the binary logistic regression, the dependent variable Hypertension) was dichotomized by coding the presence of Hypertension as '1' and otherwise was coded as '0'. The explanatory variables were thereafter tested with dependent variable one after the other (univariate binary logistic regression). All factors found statistically significant in the univariate logistic regression were afterward used in a multivariate logistic regression (Stage 2) to identify the predictors of hypertension in the study population. All analyses were conducted with SPSS version 22 and p-values < 0.05 were considered significant.

Sociodemographic characteristics of participants
A total of 244 doctors participated in the study, of which about a third were women (29.9%), most were below age 30 years (40.2) and married (54.9%). About one fifth were very senior doctors in the consultant/professor cadre (18.9) and a third have worked for eleven years and more as medical practitioners. The mean age of participants in the study is 37.4years (SD -11.3 years) and mean duration of practice is 9 years (SD -11.1 years). Okoro  Blood pressure categories as classified by AHA 2017 Table 2 shows that almost 2 in every 3 of the participants (63.1%) were considered hypertensive by the AHA 2017 classification. While about 169 participants (69.2%) had normal or elevated systolic blood pressure, only 95 participants (38.9%) were so classified by the diastolic blood pressure. Most participants (61.1%) were classified as hypertensive because of their diastolic blood pressure.

History of Hypertension among study participants
Prior to the study 13.5% of medical practitioners who participated in the study have been diagnosed as hypertensive and have managed hypertension for a mean duration of 8.7 years (SD -5.6 years) with calcium channel blockers (72.7%) and thiazide diuretics (54.5%) as the commonly used drugs (Table 3).  Table 4 reveals that about a third of participants consume alcohol (33.2%), take fruits daily (33.2%) and engage in exercise (31.1%). Two in every five participants consider their salt intake as moderate (41.0%) and perceive their level of stress as severe (42.2%). More than half sometimes take soda drinks (52.5%). Only 2 study participants had been diagnosed diabetic and were on anti-diabetic medications. Sociodemographic characteristic and hypertension as classified by AHA 2017 2 2 From Table 5, sex (X = 4.20;df -1; p -0.040), age (X = 11.73;df -4; p -0.020), marital status 2 2 (X = 6.32;df -1; p -0.012), work cadre (X = 6.18;df -1; p -0.045) and duration of practice 2 (X = 17.69;df -5; p -0.003) were significantly associated with the occurrence of hypertension in the study.

Modifiable Risk factors and hypertension as classified by AHA 2017 2
Only intake of salt (X = 8.02; df -3; p -0.046) demonstrates a statistically significant association with hypertension ( Table 6)   Table 7 displays the results of the univariate binary logistic regression between explanatory variable in the study and the occurrence of hypertension. Men (OR -1.79;95%CI:1.02 -3.13;p-0.041) and married participants (OR -1.96;95% CI: 1.16 -3.32;p -0.012) are more likely to be hypertensive than the women and single participants respectively.  However, in the multivariate binary logistics regression, in which all variables statistically significant in the univariate regression were used, the age of participant (OR -1.05;95%CI:1.02 -1.08;p -0.001) was the only statistically significant variable showing age as the most important predictor of occurrence of hypertension in this study (Table 8). risks of mortality, stroke, and end-stage renal disease, BP ranges of 120 to <130 and 70 to <80 mm Hg are 26 associated with the lowest mortality risk. Prior to the study, only 13.5% of medical practitioners who participated in the study had been diagnosed as hypertensive using BP cut off ≥140/90mmHg and had managed hypertension for a mean duration of 8.7 years (SD -5.6 years) using mostly calcium channel blockers (72.7%) and thiazide diuretics (54.5%). Community surveys in Nigeria show less than 30% of the general 29,30 population are aware of their blood pressure status. Calcium channel blockers and thiazide diuretics are the most prescribed anti-hypertensive classes in Nigeria 31--33 according to several studies and are first line drugs in 5,34,35 the treatment of hypertension.

Predictors of hypertension among study participants
Higher work cadre and duration of practice were significantly associated with the occurrence of hypertension in the study. The association of higher work cadre and duration of practice has been 13,[36][37][38][39] demonstrated in several studies. This is likely 40 because of advancing age that comes with seniority and less physically demanding routines of senior cadre 1,41-45 doctors.
Advancing age was shown to be the most important predictor of occurrence of hypertension in the study. Advancing age is an established risk factor for [42][43][44] hypertension and cardiovascular disease. Also significantly associated with the occurrence of hypertension in the study was salt intake. Added salt to prepared meals has been shown to increase the risk of [46][47][48] hypertension and CVD. . The study also showed men and married participants are more likely to be hypertensive than the women and single participants. This is in contrast with several studies which show higher risk of hypertension in single persons, with never married men having on average, higher SBP and DBP than married men and higher risk of 49,50 hypertension. Protective role of marriage has been linked to the social and psychological support it may 51,52 offer. However, several other studies have also found 53,54 a high prevalence of hypertension in married persons.
Possible reasons included obesity, short nighttime sleep duration, stress related to a high number of children/dependents, discordance in marriage leading 54,55 to stress, abnormal eating and drinking behavior. Increasing waist circumference was also associated with an increased likelihood of hypertension on univariate analysis. This finding agrees with several studies showing WC (which is an indirect measure of 56-visceral obesity) is a useful predictor of hypertension.

CONCLUSION
The use of the 2017 ACC/AHA hypertension guidelines for diagnosis of hypertension with a blood pressure cut off ≥ 130/80 mmHg resulted in a marked increase in the prevalence of hypertension in medical doctors compared to other guidelines that use a cut off value of 140/90mmHg (63.1% versus 25%). Increasing age is a significant predictor of hypertension in medical doctors. Careful consideration needs to be given to what guidelines are best suited for our local settings to diagnose hypertension and intervene early enough and appropriately.

Limitations of the study
The population from which our sample was drawn is the Medical Doctors practicing their profession in the state of Bayelsa in the Niger Delta region of Nigeria. We think a sample size of 244 participants spread across different segments of practice and cadre of physicians is not too small to study the population in question. However, generalization of the findings from this study on the entire population of Bayelsans should be done with caution.