Chapter 2. Related Work
2.3 Representation Learning Approaches
2.3.4 Sequential Models
2.3.4.2 Infinite hidden Markov model
Interviewer administered questionnaires (Appendix B) were used to collect data on demography, family and social history, main dietary components in the past, physical examination and laboratory investigations. Data on demography included the clients age, sex, marital status, level of education (none, primary, secondary, tertiary and Islamic), occupation, average estimated family monthly income (total money earned in a month), number in household (total number of persons eating from the same pot), and religion. Data on family and social history included family history of type 2 diabetes mellitus, history of significant alcohol ingestion, history of cigarette smoking, history of work related physical activity and family history of obesity.
Work related physical activity was separated into three (3) categories or grades according to occupations defined by the NCD Survey.
(1) Not active (sedentary) e.g. office work and unemployment.
(2) Moderately active e.g. house work, trade, nursing.
(3) Very active e.g. sports and laboring.
Leisure activity was graded as follows:
(1) Not active e.g. house bound
(2) Moderately active e.g. gardening, walking, and sports 1 – 2 days/week (3) Very active e.g. sports 3 days/week.
Alcohol drinkers were categorized into76
(1) Heavy drinkers ( > 2 drinks/day during the week and/or > 8 drinks on weekend) (2) Light drinkers (occasionally drink)
A drink was defined as 1 bottle of beer or a glass of wine or 1 calabash (500ml) of locally brewed beer76. In the US, a standard drink is any alcoholic beverage that contains 0.6 fluid ounces (14 grams) of pure alcohol. That equals about 1.2 table spoons of pure alcohol (12oz of beer or wine)
77.
Main component of the patients’ diet was also assessed.
Physical and general examination was done for each client. Emphasis was laid on the legs for ulcers, skin for boils/scars, eyes for complication, and extremities for numbness.
Height:
The height was measured with a Standiometre in metres to the nearest 0.1 metre. The subjects were asked to be barefoot and wear light clothing. Subjects were asked to stand straight with weight distributed evenly on both feet, heels together and the head positioned so that the line of vision is perpendicular to the body. The arms hung freely by the sides, and the head, back and buttocks and heels in contact with the vertical rod. The adjustable calibrated rod was lowered onto the topmost point on the head (without head gears) with sufficient contact with the hair.181Weight:
The weight was recorded to the nearest 0.1kilogram using a weighing scale (beam balance) without shoes and with the patient wearing light clothing, and also in fasting state181. This was done twice and a mean recorded. The Body Mass Index was calculated as weight in Kg divided by the square of height in metres expressed as Kg/m2 (104). BMI categories by WHO were defined as < 18.5 being underweight, 18.5 – 24.99 as normal, 25.0 – 29.9 as overweight, > or = 30 as obese, 30.00 – 34.9 as class I (moderate risk) obesity, 35.00 – 39.99 as class II (high risk obesity) and >or = 40 as class III (very high risk) obesity181-185.
Waist circumference (WC):
With the aid of a non stretch dress makers tape, the waist circumference was taken (in centimetres) midway between the inferior margin of the last rib (lower costal margin) and the iliac crest in a horizontal plane. The subjects stood comfortably with theirweight evenly distributed on both feet. Each landmark was palpated and marked and the midpoint determined with a tape measure. The circumferences were measured to the nearest 0.1cm at the end of normal respiration.181 WC of ≥ 88cm in females and ≥ 102cm in males was defined as abnormal by WHO181.
Hip circumference (HC):
This was measured to the nearest 0.1cm at the level of the greater trochanters (round the buttocks posteriorly and the pubic symphysis anteriorly) using a non stretch dress makers tape, with the subjects wearing underwear or light clothing. The subjects stood erect with arms at the sides and feet together. The greater trochanters were located, and the tape placed around against the skin without compressing the soft tissues. A normal value for hip circumference was not stated by the WHO.Waist-to-Hip Ratio (WHR) was
calculated as waist circumference in (cm) divided by hip circumference in (cm).181-185 WHR of ≥ 1 in males and ≥ 0.85 in females is defined as abdominal/central obesity by WHO181.Blood pressure measurement:
Blood pressure was measured with a standard mercury sphygmomanometer with the patient in a sitting position and the arm resting on the table at the same level of the heart. Patient was engaged in discussion for at least 5 minutes before the blood pressures were taken. Systolic and diastolic blood pressures were taken at the appearance and disappearance of the Korotkoff sounds (phase I and V) respectively.183Blood samples:
were drawn from a forearm vein of each study and control subject seated and relaxed. Samples were put into Fluoride-oxalate tubes, kept on ice and transported within 20 minutesof collection to the Chemical Pathology Laboratory, located within the hospital, for fasting plasma glucose determination. Plasma glucose was analyzed by a specific glucose oxidase method using 4-amino phenazone as oxygen acceptor. The principle of the test is as follows:Glucose oxidase is a specific enzyme which promotes the oxidation of glucose to glucoronic acid with the production of an equivalent amount of hydrogen peroxide (H2O2). In the presence of peroxidase, oxygen from hydrogen peroxide is transferred to a suitable receptor (4-amino phenazone) with the production of a coloured complex, the intensity of which is proportional to the concentration of glucose in the plasma sample. The reaction is as follows:
Glucose +2H2O→→glucose oxidase→→ Gluconic acid + 2H2O2
H2O2→→peroxidase→→ H2O + O (nascent oxygen)
O + 4-Aminophenazone + phenol→→→→ Red-violet solution.
The intensity of the colour formed was measured spectrophotometrically at 520nm.
Plasma glucose = optical density (OD) of sample/OD of standard × Concentration of standard.
The blood samples were centrifuged at 2,500 revolutions per minute for 2-3 minutes and the plasma separated and stored at -20oC until analyzed. Glucose level estimation carried out thus:
2.5ml of solution containing glucose oxidase, 4-aminophenazone and peroxidase was added to a test tube and mixed with 50µL of plasma (which could have been allowed to thaw or warm up to room temperature) and 2.5ml of phenol reagent. The mixture was then incubated in a water bath at 37oC for 20 minutes. Thereafter, the tubes with the mixture were allowed to cool down to room temperature. The mixture then changed from an almost colourless to red-violet (pinkish) solution depending on the glucose concentration. The absorbance (optical density – OD) was then read off on the spectrophotometer at a wavelength of 520nm with that for the standard glucose solution (of known concentration) which would have been similarly incubated with glucose oxidase and phenol.
For each set of samples, the mean OD of duplicated standard solutions of known concentration was utilized in calculating the plasma glucose level. Every tenth plasma sample was assayed in duplicate (coefficient of variation = 1.0%).
Formula used in calculating coefficient of variation (CV) = SD/mean × 100, Where SD = standard deviation,
And mean = mean of plasma glucose concentration.
3.10.0 DEFINITION OF TERMS
3.10.1 Diabetes mellitus is diagnosed by one or more of the following criteria recommended By ADA and adopted by WHO.48
(a) Random or casual plasma glucose concentration > or equal to 11.1 mmol/L in the presence of classical symptoms of polyuria, polydipsia and unexplained weight loss.
(b) Fasting plasma glucose > 7.0mmol/L
(c) 2hours plasma glucose > or equal to 11.1 mmol/L after 75g of oral glucose load (OGTT).
In the absence of symptoms or unequivocal hyperglycaenia with acute metabolic decompensation, one of these three tests should be repeated on a different day to confirm diagnosis.
3.10.2 Type 2 diabetes - Persons diagnosed to have diabetes using the above criteria who are > 30 years at diagnosis and who show initial response to Oral Hypoglycaemic Agents (OHA) and absence of ketonuria.
3.10.3 Oral Glucose Tolerance Test (OGTT) – Plasma glucose concentration after 75g oral glucose load with subjects on a diet of 150g minimum carbohydrate content for at least 3 days preceding performance of the OGTT186
3.10.4 Impaired Glucose Tolerance (IGT) – Plasma glucose concentration between 7.8-11.0mmol/L two hours after 75g oral glucose load.
3.10.5 Impaired Fasting Glycaemia (IFG) – Plasma glucose concentration between 6.1-6.9 mmol/L after 8-12 hours fast.
3.10.6 Normal Glucose Tolerance (NGT) - Plasma glucose < 7.8 mmol/L 2 hours after 75g oral glucose and/or fasting plasma glucose of < 6.Ommol/L
3.10.7 First Degree Relative (FDR) - Parents (father, mother) siblings (brothers, sister) and offspring’s (son, daughters).
3.10.8 Random or casual is defined as any time of the day, without regard to the time of last meal.
3.10.10 Probands: Persons with type 2 diabetes whose first degree relatives are studied.
3.10.11 Waist circumference < 102cm and > 102cm were classified as normal and abnormal in males, < 88cm and > 88cm were classified as normal and abnormal for females137-141 respectively.
3.10.12 Waist-to–hip ratio < 0.9 and > 0.9 were classified normal in males and < 0.85 and > 0.85 normal and abnormal females respectively.137-141