Prospective observational studies and related SRs and MAs of studies relating normal-weight central obesity to mortality
| STUDY AND YEAR | STUDY TYPE (DURATION) | STUDY OBJECTIVES | NO. AND AGE OF PARTICIPANTS | RESULTS | COMMENTS |
|---|---|---|---|---|---|
| Coutinho et al, 201343 | SR of prospective observational studies and collaborative analysis (0.5–7.4 y) | Relation of measures of central obesity to mortality | 15 923 patients with known CAD Mean (SD) age 65.7 (11.5) y | Highest mortality category combined lowest BMI with highest WHR or WC; HR = 1.7 | Central obesity associated with equal increase in mortality risk in lean and obese patients. Increased BMI was associated with reduced risk in these patients |
| Kramer et al, 201344 | MA of prospective observational studies (3–30 y) | Relation of cardiometabolic risk and BMI category to CVD events and all- cause mortality | 61 386 adults from the general population Mean age range 44–60 y | Highest mortality or CVD event rate was similar in metabolically unhealthy normal-weight and obese participants; HR = 2.65 compared with those of normal weight and metabolic health | Did not specifically consider central obesity. Metabolic health was based on absence of metabolic syndrome components, insulin resistance, or inflammatory markers |
| Carmienke et al, 201339 | SR and regression MA of prospective cohorts (5–24 y) | Relation of measures of abdominal obesity parameters to mortality | 689 465 healthy adults Age ≥ 18 y | Highest mortality category combined lowest BMI with highest WHR or WC | WHR, WC, or WHtR combined with BMI gives best mortality prediction. In participants > 65 y there was a non-significant or negative association with increasing BMI, WC, and WHR |
| Folsom et al, 200045 | Prospective observational study (11–12 y) | Relation of BMI, WC, and WHR to mortality, cancer, diabetes, hypertension, and fracture | 31 702 healthy US women Age 55–69 y | Highest mortality category combined lowest BMI with highest WHR | WHR had the best mortality prediction |
| Pischon et al, 200846 | Prospective observational study (9.7 y) | Association of distribution of adiposity with risk of death | 359 387 participants from general European population Age 25–70 y | Highest mortality associated with lowest BMI percentile having highest WC or WHR | Association of BMI with mortality is J shaped. Measures of central obesity showed positive linear association with mortality when adjusted for BMI |
| Zhang et al, 200847 | Prospective observational study (16 y) | Relation of abdominal adiposity to premature death | 44 636 US women from the Nurses’ Health Study Age 30–55 y | Highest mortality category combined highest BMI and highest WC or WHR. Risk was only slightly lower for normal BMI with high central obesity | WC and WHR were both directly associated with mortality |
| Koster et al, 200848 | Prospective observational study (9 y) | Relation of WC to all-cause mortality | 245 533 US adults Age 51–72 y | Normal weight with high WC increased mortality by 22%. Exceeded only by class 2 and 3 obesity with high WC | WC used as measure of central obesity in mortality prediction |
| Reis et al, 200949 | Prospective observational study (12 y) | Relation of BMI, WHR, and WTR to mortality | 13 065 participants from the general US population Age 30–102 y | Highest mortality category combined lowest BMI with highest WHR or WTR | WHR or WTR had the best mortality prediction. No association at > 65 y of age |
| Romero-Corral et al, 200950 | Prospective observational study (8.8 y) | Relation of body fat percentage to cardiovascular mortality and metabolic dysregulation in participants with normal BMI | 6171 US patients with normal BMI and CAD Age ≥ 20 y | High body fat percentage and WC were associated with increased risk of metabolic syndrome. CVD mortality increased in normal-weight obese women (HR = 2.20) compared with nonobese women | Body fat measured by bioimpedance. Body fat percentage did not correlate with all-cause mortality in women or men at any BMI |
| Staiano et al, 201251 | Prospective observational study (13 y) | Relation of BMI, WC, and WHR to CVD and all-cause mortality | 8061 Canadian adults Age 18–74 y | No mortality increase with WC in normal-weight adults. Highest mortality in highest WC terciles of obese adults | WC had the best association with CVD and all-cause mortality |
| Thomas et al, 201352 | Prospective observational study (mean [SD] 5.6 [2.4] y) | Relation of obesity measured by BMI or WC on mortality at differing ages | 119 010 French participants with BMI > 20 kg/m2 Age 17–85 y | Mortality at BMI 20–25 kg/m2 and WC ≥ 102 cm ...
No association at age > 65 y | Mortality risk higher for central obesity in normal BMI range than in class 2 and 3 obesity. WC gives best mortality prediction at < 65 y of age. Neither WC nor BMI are useful in the elderly |
| Cerhan et al, 201453 | Pooled data from 11 prospective observational studies (median 9 y, maximum 21 y) | Relation of WC to mortality across entire range of BMI categories | 650 386 non-Hispanic white adults Age 20–83 y | Highest mortality associated with BMI ranges < 20 and ≥ 35 kg/m2 in those with highest WC. Highest WC in those with BMI 20–22.5 kg/m2 had higher mortality than those with class 1 obesity at highest WC | WC should be assessed in combination with BMI even in those in normal BMI range. WC is directly associated with mortality at all levels of BMI |
| Sahakyan et al, 201554 | Prospective observational study (14.3 y) | Relation of central obesity and survival in adults of normal body weight | 16 124 US adults with BMI ≥ 18.5 kg/m2 Age 18–90 y | Men with normal-weight central obesity had higher mortality risk than any other BMI and WHR combination. Similar women had 40% and 32% relative risk increase compared with overweight and obese women without central obesity | WHR used as measure of central obesity in mortality prediction |
| Klingberg et al, 201555 | Prospective observational study (average 6 y) | Relation of baseline WC and change in WC to morality and CVD | 2492 healthy Danish and Swedish women Age 44–74 y at baseline | Association of mortality with both high baseline WC and large increase in WC over time; particularly high in those with BMI < 25 kg/m2 | WC used in mortality prediction. Hip circumference was unrelated to mortality |
| Sharma et al, 201656 | Prospective observational study (average 7.1 y) | Relation of WC or WHR and BMI to mortality in elderly patients with CVD | 7057 elderly patients with CAD Mean age 73 y | Highest mortality in patients with normal BMI and central obesity | Highlights importance of including WC or WHR along with BMI when making adiposity-related mortality assessment |
| Hamer et al, 201757 | Prospective observational study (average 9 y) | Determine whether WHR is more predictive of mortality than BMI is | 42 702 UK adults Mean age 57.7 y | Normal weight with central obesity showed highest mortality; HR = 1.22 for death | WHR used as measure of central obesity in mortality prediction |
BMI—body mass index, CAD—coronary artery disease, CVD—cardiovascular disease, HR—hazard ratio, MA—meta-analysis, SR—systematic review, UK—United Kingdom, US—United States, WC—waist circumference, WHR—waist-to-hip ratio, WHtR—waist-to-height ratio, WTR—waist-to-thigh ratio.