Baseline characteristics

A total of 1065 healthy individuals were screened. The mean (SD) age of the participants was 42.66 (12.18) years. There were 667 (62.6%) males. The participants’ mean weight, height, and BMI were 71.69 (13.39) kg, 163.71 (10.34) cm, and 26.78 (4.61) kg/m2, respectively. The median of monthly household income in United States dollars was $177.47 (with an interquartile range of $92.28 to $234.26). Most participants were Muslims, i.e., 1034 (97.1%). In terms of family structure, it was observed that family structure observed that most of the participants were living in a nuclear family structure 492 (46.2%), followed by joint family 465 (43.7%), while 108 (10.1%) participants were living alone. Most of the study participants lived in concrete houses, i.e., 911 (85.5%), while 751 (70.5%) were working. The majority of the participants were married, i.e., 875 (82.2%) (Table S1).

Physical and psychosocial characteristics of the participants

Most of the study participants reported low physical activity, i.e., 766 (71.9%). Most participants reported rarely or never skipping breakfast, i.e., 650 (61.0%). Non-smokers were predominantly higher, i.e., 841 (79.0%). Tobacco chewing was reported by 121 (11.4%), areca nut use by 166 (15.6%), and waterpipe smoking by 21 (2.0%) individuals. Family history of diabetes was observed in 540 (50.7%), while hypertension history in the family was observed in 634 (59.5%) individuals. Anxiety was reported by 402 (37.7%), whereas suicidal ideation was by 90 (8.5%) individuals (Table S1).

Prevalence of components of MetS by various definitions

The prevalence of central obesity using IDF and modified NCEP-ATP III definitions were found to be 73.9% (95% CI: 71.1–76.5) in both definitions. Similarly, elevated plasma glucose level was similar in both IDF and modified NCEP-ATP III, i.e., 19.5% (95% CI 17.1–22.0). While elevated triglycerides prevalence, reduced HDL prevalence, and high blood pressure prevalence were found to be 19.6% (95% C.I 17.2–22.1), 49.9% (95% C.I 46.8–52.9), and 51.1% (95% C.I 48.0-54.1) respectively using all three definitions (Table 2).

Prevalence of MetS by using various definitions

The prevalence of MetS based on IDF definition was found to be 32.2% (95% C.I 29–35), by NCEP ATP III 22.4% (95% C.I 19–25), while by modified NCEP-ATP III 33.9% (95% C.I 31–36) (Table 2).

Among individuals with < 30 years of age, the prevalence of MetS based on IDF definition was found to be 22.6% (95% C.I 17.1–28.9), by NCEP ATP III 13.5% (9.1–18.9), while by modified NCEP-ATP III 25.9% (95% C.I 20.1–32.5). Among individuals 30–50 years of age, the prevalence of MetS based on IDF definition was found to be 33.1% (95% C.I 29.4–37.0), by NCEP-ATP III 23.6% (20.2–27.1), while by modified NCEP-ATP III 34.3% (95% C.I 30.5–38.2). Among individuals with > 50 years of age, the prevalence of MetS based on IDF definition was found to be 38.0% (95% C.I 31.9–44.3), by NCEP ATP III 27.2% (95% C.I 21.8–33.2), while by modified NCEP-ATP III 40.0% (95% C.I 33.9–46.4). In male individuals, the prevalence of MetS based on IDF definition was found to be 29.8% (95% C.I 26.4–33.5), by NCEP ATP III 19.2% (16.3–22.4), while by modified NCEP-ATP III 32.2% (95% C.I 28.7–35.9). In female individuals, the prevalence of MetS based on IDF definition was found to be 36.2% (95% C.I 31.4–41.1), by NCEP ATP III 27.9% (23.5–32.6), while by modified NCEP-ATP III 36.9% (95% C.I 32.2–41.2) (Table S2).

Area-wise stratification revealed that the highest prevalence of undiagnosed MetS based on all three criteria was observed in Kemari Area, i.e., 18 (41.9%) through IDF and modified NCEP-ATP III definition, whereas 12 (27.9%) through NCEP-ATP III (Table S3).

Comparison of MetS prevalence based on IDF with sociodemographic, physical, and psychosocial characteristics of the participants

Individuals with MetS had a significantly higher mean age (p-value < 0.001) and BMI (p-value ˂0.001) compared to individuals without MetS. Moreover, a significant association of MetS was observed with gender (p-value 0.032), current working (p-value 0.001), marital status (p-value 0.024), smoking status (p-value < 0.001), areca nut use (p-value 0.023), physical activity (p-value 0.037), and family history of hypertension (p-value 0.048) (Table 3).

Comparison of MetS prevalence based on NCEP ATP III definition with sociodemographic, physical, and psychosocial characteristics of the participants

Individuals with MetS had a significantly higher mean age (p-value 0.001) and BMI (p-value < 0.001). Moreover, a significant association of MetS was observed with gender (p-value 0.001), religion (p-value 0.031), current working (p-value 0.001), marital status (p-value 0.048), smoking status (p-value < 0.001), and physical activity (p-value 0.002) (Table 3).

Comparison of MetS prevalence based on modified NCEP ATP III definition with sociodemographic, physical, and psychosocial characteristics of the participants

Individuals with MetS had a significantly higher mean age (p-value 0.001) and BMI (p-value < 0.001). Moreover, a significant association of MetS was observed with current working (p-value 0.002), smoking status (p-value < 0.001), areca nut use (p-value 0.039), physical activity (p-value 0.002), and family history of hypertension (p-value 0.041) (Table 3).

Regression analysis of variables associated with undiagnosed MetS

The findings of the multiple binary logistic analysis revealed that after adjustment of other covariates, based on IDF definition, the odds of prevalence of undiagnosed MetS was significantly higher in individuals with increased BMI (ORadj 1.13, 95% CI 1.09–1.17), areca nut use (ORadj 1.71, 95% CI 1.19–2.47), and current smoking (ORadj 2.54, 95% CI 1.73–3.73). Based on NCEP-ATP III criteria, the odds of prevalence of undiagnosed MetS were significantly higher in female individuals (ORadj 1.85, 95% CI 1.24–2.78), increased BMI (ORadj 1.15, 95% CI 1.11–1.19), current smoking (ORadj 3.77, 95% CI 2.47–5.75), and low physical activity (ORadj 1.56, 95% CI 1.08–2.26). Based on the modified NCEP ATP III definition, the odds of prevalence of undiagnosed MetS were significantly higher among individuals with increased BMI (ORadj 1.12, 95% CI 1.08–1.15), areca nut use (ORadj 1.58, 95% CI 1.10–2.72), current smoking (ORadj 2.24, 95% CI 1.55–3.21), and low physical activity (ORadj 1.36, 95% CI 1.01–1.84). Yet, the odds of prevalence of undiagnosed MetS were significantly lower in individuals currently working (ORadj 0.70, 95% CI 0.52–0.95) (Table 4).

Sensitivity and specificity analysis

Kappa statistics revealed a substantial agreement between IDF and NCEP-ATP III definition (k = 0.645, p-value < 0.001). A strong agreement was observed between IDF and modified NCEP-ATP III guidelines (k = 0.960, p-value < 0.001). Modified NCEP-ATP III was more sensitive than NCEP-ATP III, i.e., 94.7% and 62.7%, respectively (Table 5). Age and gender-wise stratification revealed similar findings (Table S4).

Table 2 Prevalence of components of undiagnosed metabolic syndrome among apparently healthy individuals living in Karachi, Pakistan in the year 2022Table 3 Comparison of demographic and clinical features of apparently healthy and undiagnosed metabolic syndrome individuals living in Karachi, Pakistan in the year 2022Table 4 Logistic regression analysis of variables associated with undiagnosed metabolic syndrome among individuals living in Karachi, Pakistan in the year 2022Table 5 Sensitivity, specificity, and level of agreement of NCEP ATP III and modified NCEP ATP III for MetS using IDF as standard definition