This was a hospital-based unmatched case control study, conducted in the largest tertiary care hospital in Gampaha district during the period of 1st of June to 31st of August 2019. The hospital has four medical wards, five surgical wards, and three obstetrics and gynecology wards. The case group included the patients admitted to Medical, Surgical, and Gynecology wards, and who were newly diagnosed to have fatty liver disease or diagnosed with a fatty liver disease within the last six months or less by ultrasonography.
NAFLD was diagnosed based on established ultrasound findings which included increased echogenicity of the liver compared to kidney and spleen, obliteration of vascular architecture, and deep attenuation of ultrasonic signals. An individual was diagnosed as a NAFLD patients when he/she showed at least two of the above mentioned findings.15 Four well-trained medicals officers at the radiology department in the hospital were involved in the diagnostic process. The control group included patients who were not diagnosed to be having fatty liver disease by ultrasonography. The exclusion criteria for both cases and controls were the patients who consumed alcohol above the safe limit including both current and former drinkers, pregnant women, pediatric age groups (≤14 years of age), patients who had been diagnosed with diseases such as hepatitis, cirrhosis, liver metastasis and liver cancers, cholestasis, alcoholic liver disease, and dengue hemorrhagic fever.
Sample size calculation was done considering odds ratio as 1.96 for elevated triglyceride for NAFLD,11 the anticipated proportion of elevated triglyceride among controls as 46%, power as 80%, and with 5% significant level. The control per case ratio was 2:1. According to the calculation, a minimum of 101 cases and 202 controls were needed. After adding 5% for the non-responders, it was decided to recruit 106 cases and 212 controls. Those who fulfilled inclusion criteria were recruited consecutively until the required sample size was achieved.
The study instruments were, a pre-tested interviewer-administered questionnaire (IAQ) and a record sheet. The IAQ has three parts; part 1- assessed socio-demographic factors, part 2- assessed medically related factors, and part 3- behavioral factors (Tea, Coffee, and Fast food consumption, Physical activity level, Alcohol consumption). The face and content validity of the questionnaire was assured. The validated global physical activity questionnaire (GPAQ) was used to access the physical activity levels.16 The validity of the GPAQ ranged from low to moderately high (r =0.25-0.63).17 Pretesting was done at a radiology unit of another hospital with the patients who were subjected to an abdominal ultrasound scan. The record sheet was used to record the hemoglobin level, height, and weight. The height was measured by using a standard measuring tape. The weight was measured by using a calibrated scale.
Data collection was done at the Radiology department of the hospital by the first author. Before the data was collected prior permission was obtained from the consultant radiologist. The ultrasound scan was done using 5MHz 50mm convex probe which was made in china.
The safe limit of alcohol consumption was assessed based on Asian standard values which were 14 units per week for men and 7 units per week for women.18 One unit of alcohol is included in 25-30 ml of arrack or whiskey, 50ml of illicit alcohol, a half-pint of beer or toddy, 175ml glass of wine. Those were taken into account for calculating units of alcohol per week.18 Hypertension, diabetic Mellitus, and dyslipidemia status were cross-checked with the Bed Head Tickets.
According to Body Mass Index (BMI) cut off values specified for Asians, an individual with a BMI value ≥ 23 kg/m2 was considered as overweight.19 The physical activity level was assessed by using three types of activities. They include activity at work, physical activity involved travelling to and from places, and physical activities during recreational activities. It was calculated by using Metabolic Equivalent (MET). Moderate intensity physical activity of 150 minutes or Vigorous-intensity activity of 75 minutes or combination of moderate and vigorous-intensity physical activity achieving at least 600 MET minutes a typical week is essential to be regarded as an adequate level of physical activity. MET minutes were calculated in a case of combined activity as follows.
Moderate intensity activity MET min/week = 4.0 x Moderate intensity activity minutes x Moderate activity days. Vigorous-intensity activity MET min/week = 8.0 x Vigorous intensity activity minutes x Vigorous-intensity activity days and Walking/cycling MET min/week equals 3.3 x walking/cycling minutes x Walking/Cycling days.16 If the participant has not fulfilled the above criteria it was taken as an inadequate level of physical activity .
The frequency of tea consumption was divided into two groups. Consumption of >4 cups per day and consumption of ≤4 cups per day. Coffee consumption was classified as ≥1 cups per day or none use per day.11,20 Hamburgers, hot dogs, pizza, fried chicken, french fries, processed fish, instant noodles, and pastries were classified under fast food. The frequency of fast food consumption was divided as ≥2 time and the <2 time per week.21 The average hemoglobin value among Asian women was 11 to 13 g/dl and among men, it was 13 to 15 g/dl. In females, hemoglobin level greater than 13g/dl is considered as High Blood Hemoglobin Level whereas in males hemoglobin level greater than 15g/dl is considered as High Blood Hemoglobin Level . Familial risk was determined based on the self-reported health history for first- and second-degree relatives. A patient was considered to be having a family history for a liver disease if any family member either from maternal or paternal side had suffered or is having an any kind of a liver disease condition such as fatty liver, cirrhosis, NASH, etc.
The statistical analysis was done by using SPSS 16 version. The results were expressed as odds ratios (OR), 95% confident intervals (95% CI), and the p values. The variables with p-value <0.2 in the bivariate analysis were selected for the multiple logistic regression. The purposeful selection was used. Hosmer and Lemeshow test was used as the test for goodness of fit and it was observed as satisfactory (chi-square 4.48, p value=0.61)
The permission was taken from the Director of the hospital and the consultants and the interview was conducted after obtaining the informed written consent of the patients. Further, measures were taken to minimize the disturbances to the routine ward works. The data collection was done by avoiding the routine daily ward round times. Ethical clearance was taken from the Ethics Review Committee at the Postgraduate Institute of Medicine, Colombo.