Study design and setting
A cross sectional study was conducted between June 2021 and October 2021 at an institutional primary care specialist clinic located in Gombak district Selangor, Malaysia. This clinic located at an urban area which covers an area of 839.1 km2 with a dense total population of 629,971 (29). The services provided include chronic diseases, acute care, adolescent clinic, and health screenings by a multi-disciplinary team consisted of family physicians, registrar of family medicine postgraduate programme, nurses, pharmacists, dieticians, and administrative staffs. The clinic also served as a teaching clinic for the medical undergraduates.
Participants and Sampling
Adult male patients who had their follow-up between 1st June 2021 and 30th October 2021 were eligible to participate in the study. The inclusion criteria were: men aged ≥40 years, diagnosed to have MetS by the Joint Interim Statement (JIS) criteria (30) (see box 1), able to read and understand Malay or English language, and had blood tests (fasting plasma glucose, fasting serum lipid, and HbA1c) at least 6 months prior the conduct of the study. Sampling was done via computer generated simple random sampling method.
Box 1: Diagnostic criteria of Metabolic Syndrome (MetS) based on JIS 2009 criteria
The exclusion criteria were: (i) established diagnosis of psychiatry illness or were mentally challenged (e.g., depression and anxiety disorder); (ii) presence of residual weakness from stroke (e.g., unilateral weakness, pure motor stroke, and sensory-motor stroke); (iii) past history of surgical treatment for ED (e.g., penile prostheses); (iv) patients who received hormone therapy for ED (e.g., testosterone therapy); (v) patients who were on anti-hypertensives (e.g., thiazide diuretics and beta blocker), antidepressants (e.g., selective serotonin reuptake inhibitors and tricyclics), antipsychotics (e.g., neuroleptics), and antiandrogens (e.g., GnRH analogues and antagonists); (vi) current injury or history of wrist and hand injury in the past 1 month; (vii) history of wrist and hand surgery in the past 3 months.
The sample size was calculated using single proportion formula based on the objective of the study. According to Abdul Rahman et al, the prevalence of ED among adult males aged 40-76 years old was 69.5%. (5) Taking the alpha value of 0.05 with confidence interval of 95%, the minimum required sample was 304 patients. Considering a 15% non-response rate, the final sample was 350 participants.
A four-part questionnaire was devised for data collection. The sociodemographic and medical history section was constructed to obtain information of participant’s age, ethnicity, education level, marital status, household income, smoking and alcohol status and comorbid history. Clinical examinations such as weight, height, body mass index (BMI), waist circumference (WC), blood pressure (BP), and HGS were performed and documented. The blood profile results including fasting plasma glucose, fasting serum Lipid, and HbA1c were obtained from electronic medical record (EMR) and International Index of Erection -5 (IIEF-5) was used to measure ED.
HGS was determined using a Jamar dynamometer (Sammons Preston, Bolingbrook, IL, USA) according to a standardised protocol (31). The arm was positioned vertically to the body with the elbow flexed to 90º while holding the dynamometer. The participant was instructed to squeeze the device as hard as possible for three seconds. The measurement was repeated thrice at 30 second intervals. Each participant's dominant hand was measured three times. In this study, the highest measurement obtained for the dominant hand was used (26). The reference range of HGS was developed in a large epidemiological study in United Kingdom in 2014 involving 60,803 respondents, including 49,964 male participants and 26,687 female participants from 12 general population studies in Great Britain, where centile curves were produced based on age for ages 4 to 90 years (26). The result of HGS within each stratum was displayed in centile, stratified according to age and gender.
The IIEF-5 questionnaire was bilingual with both English and Malay. Lim et al. adapted and validated the Malay version of the IIEF-5 in 2003 (32). The sensitivity and specificity of the IIEF-5 questionnaire were 85% and 75%, respectively, with a Cronbach alpha of 0.9 (32).The IIEF-5 consisted of five items, where each item was scored on a five or six-point scale, ranging from zero to five. The total score ranged from 1 to 25. The presence of ED was indicated by IIEF-5 scores that were equal or less than 21. The severity of ED was further categorised based on the IIEF-5 scores: severe (5–7), moderate (8–11), mild to moderate (12–16), mild (17–21), and no ED (22–25).
The dependant variable for the study was presence of ED as diagnosed using the IIEF-5 questionnaire. Age, ethnicity, marital status, household income, education level, smoking, alcohol intake, presence of comorbidity, waist circumference (WC), obesity, HSG, and blood profiles were the independent variables. Malay or non-Malay ethnicities were distinguished. Marital status was grouped as either married or single/divorced/widowed. Meanwhile, household income was divided into i) high (T20) and middle income (M40) if ≥ RM4,850/household; or ii) low income (B40) if < RM4,850/household. These classification were developed in 2019 according to the Household Income and Basic Amenities Survey Report, 2019 (33). While education level was categorised into; i) secondary and below; or ii) tertiary. Secondary and below education level is defined as either having no formal education or has attended primary and/or secondary school from the age of seven years up to 17 years old. Meanwhile, tertiary education is defined as any education pursued beyond secondary school including universities and colleges. Regarding alcohol consumption, alcohol drinker are defined as those who drink alcohol daily, weekly or occasionally for the past 12 months in the past one year (34). Non-drinker is defined as those who did not drink any alcohol in the past one year. For smoking status, participants were classified as ever smoked if they were currently smoking or an ex-smoker who had at least stopped smoking in the past 30 days. Whereas, never smoked is defined as those who had never smoked in the past. Hypertension, diabetes mellitus (DM), and coronary artery disease, cerebrovascular accidents were present if these diagnoses were recorded in the EMR, or participants were on medication for these conditions. Dyslipidemia was identified via patient self-report of diagnosis of ‘high cholesterol’, cholesterol-lowering medication taken, or any elevation of fasting serum lipid. The definition of elevation of fasting serum lipid were as follows: Total cholesterol (TC) > 5.2 mmol/L, high density lipoprotein – cholesterol (HDL-C) < 1.0 mmol/L (males) or < 1.2 mmol/L (females), Triglycerides (TG)> 1.7 mmol/L, and elevated low density lipoprotein – cholesterol (LDL-C) levels (35). The LDL-C levels will depend on the patient’s cardiovascular risk. (35). (See box 2).
Box 2: Risk Stratification of Cardiovascular (CV) Risk and Target LDL-C Levels.
Weight and height were measured using Secca 767 and were expressed as kilogram(kg) and centimeter (cm) respectively. WC was measured to the nearest 0.1 cm by using non-stretchable measuring tape with the participants standing in a relaxed position and arms at the side. The measurement was taken at the midpoint between the lower rib margin (12th rib) and the iliac crest. Obesity was defined as BMI ≥ 27.5 kg/m2 (36).
This study employed a simple random sampling method. A list of all male patients who had their follow-up between 1/1/2020 and 31/12/2020 at the clinic were obtained from the IT Unit. All male patients who were classified as MetS based on the JIS criteria were randomly sampled using a computer-generated random sampling number. Their presence on the follow-up day was confirmed by phone call. On the patient’s follow-up day, they were given the patient’s information leaflet (PIL) and consent form and their eligibility according to the inclusion and exclusion criteria were done. Eligible participants who consented were given a data collection form and were examined. Data were collected by a trained research assistant to guarantee a uniform data gathering procedure. Figure 1 illustrate the flowchart for this study.
The IBM® Statistical Package for Social Sciences (SPSS) version 27 software (IBM Corp., Armonk, NY, USA) was used for data entry and statistical analysis. The sociodemographic characteristics, clinical profiles, and prevalence of erectile dysfunction among men with MetS were described using descriptive analysis. The continuous data were described either in terms of mean with standard deviations (SD) or median with interquartile ranges (IQR) based on normality of distribution. The categorical data was described using frequencies and percentages. To identify the factors associated with erectile dysfunction, inferential analysis was used. Odds ratios (OR) and their 95% confidence intervals (CI) were calculated using simple logistic regression (SLogR) and multiple logistic regression (MLogR). Variables with a p-value that was <0.25 from the SLogR were subsequently included in the MLogR. The MLogR was performed using the forward binary logistic regression method. Model fitness was checked using the Hosmer−Lemeshow goodness-of-fit test. Interactions, multicollinearity, and assumptions were also checked. Statistical significance was taken at a p-value that was <0.05.