Validation of a weight history questionnaire to identify adolescent obesity

Sources and severity of bias in estimates of the BMI-mortality association

Estimates of mortality differences by body mass index (BMI) are likely biased by: (1) confounding bias from heterogeneity in body shape; (2) positive survival bias in high-BMI samples due to recent weight gain; and (3) negative survival bias in low-BMI samples due to recent weight loss. I investigate these sources of bias in the National Health and Nutrition Examination Survey (NHANES) 1988-94 and 1999-2006 linked to mortality up to 2015 (17,784 cases; 4,468 deaths). I use Cox survival models to estimate BMI differences in all-cause mortality risks among adults aged [45-85) in the United States. I test for age-based differences in BMI-mortality associations and estimate functional forms of the association using nine BMI levels. Estimates of the BMI-mortality association in NHANES data are significantly affected by all three biases, and obesity-mortality associations adjusted for bias are substantively strong at all ages. The mortality consequences of overweight and obesity have likely been underestimated, especially at older ages.

Five-year kidney outcomes of bariatric surgery differ in severely obese adolescents and adults with and without type 2 diabetes

Bariatric surgery improves markers of kidney health in severe obesity, yet it is unclear if kidney disease outcomes differ according to age at surgery. Therefore, we examined health effects of Roux-en-Y gastric bypass between 161 adolescents and 396 adults participating in two related but distinct studies. Primary outcomes were elevated urine albumin-to-creatinine ratio (UACR) of 30 mg/g or more and hyperfiltration (an estimated glomerular filtration rate of 135 ml/min/1.73m² or more). Analyses were stratified by the presence of pre-operative type 2 diabetes. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of elevated UACR prior to surgery compared to adults (22.5 vs. 9.0%). Resolution of elevated UACR following surgery differed between adolescents and adults with type 2 diabetes, with adolescents experiencing a significantly earlier improvement following surgery. Adolescents without pre-operative type 2 diabetes demonstrated a significantly increased prevalence of UACR prior to surgery compared to adults (9.4 vs. 4.5%), with no improvement occurring in either group post-operatively. Adolescents with pre-operative type 2 diabetes had a significantly increased prevalence of hyperfiltration that remained throughout the study period, whereas hyperfiltration prevalence was similar among those without type 2 diabetes. Thus, adolescents with pre-operative type 2 diabetes experienced earlier attenuation of elevated UACR compared to adults with pre-operative type 2 diabetes in response to gastric bypass.

Validity of self-reported recall of anthropometric measures in early life: A systematic review and meta-analysis

Overweight and obesity in early life are risk factors for many adult-onset chronic diseases. The objective of this study was to assess the validity of self-reported recall of early life anthropometric measures. A systematic review was conducted by searching four electronic databases (PubMed, ProQuest, EMBASE, and MEDLINE). Studies were eligible if they evaluated the validity or reliability of self-reported recall by adults of their own body mass index, height, and/or weight during earlier life periods. Meta-analyses were conducted to pool correlation coefficients and mean differences. There were 15 studies included with a total of 17 477 participants. The mean pooled difference between self-reported recall of BMI compared with prospective measures was 0.06 kg/m² (95% CI, -0.62 to 0.73), and the pooled correlation coefficient was 0.72 (95% CI, 0.65-0.79). Self-reported weight was also strongly correlated with reference standard measures (pooled r = 0.83; 95% CI, 0.72-0.90) with a small mean difference (0.87 kg; 95% CI, 0.19-1.56; I² = 91%). Despite significant heterogeneity, the findings from this review suggest self-reported recall of early life body mass index, height, and weight may be valid measures. This evidence may inform life-course epidemiology studies considering the use of retrospective assessment of self-reported anthropometry.

Trajectories of body mass index, from adolescence to older adulthood, and pancreatic cancer risk; a population-based case-control study in Ontario, Canada

PURPOSE

Pancreatic cancer has the highest fatality rate of all cancers. Adulthood obesity is an established risk factor for pancreatic cancer; however, life-course obesity is not well understood. The aim of this study was to evaluate the association between body mass index (BMI) trajectories throughout the life-course and pancreatic cancer risk.

METHODS

A population-based case-control study was conducted (2011-2013) in Ontario, Canada. Cases were recruited from the Ontario pancreas cancer study (n = 310) and controls from the Ontario cancer risk factor study (n = 1258). Questionnaires captured self-reported height and weight at four timepoints (adolescence, 20 s, 30-40 s, 50-60 s). BMI trajectories were identified using latent class growth mixture modeling. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from multivariable logistic regression.

RESULTS

Five BMI trajectories were identified: stable-normal weight (38.9%), progressively overweight (42.2%), persistent overweight (12.6%), progressive obesity (4.2%), and persistent obesity (2.1%). The persistent overweight (OR = 1.55; 95% CI 1.02, 2.39) and progressive obesity trajectories (OR = 1.49; 95% CI 0.77, 2.87) compared to stable-normal weight were associated with increased odds of pancreatic cancer. When BMI was evaluated separately the strongest associations with pancreatic cancer emerged in young and mid-adulthood.

CONCLUSION

BMI trajectories characterized by overweight in early adulthood were associated with increased pancreatic cancer risk suggesting a life-course approach to disease risk.

Five-Year Outcomes of Gastric Bypass in Adolescents as Compared with Adults

BACKGROUND

Bariatric surgery results in weight loss and health improvements in adults and adolescents. However, whether outcomes differ according to the age of the patient at the time of surgery is unclear.

METHODS

We evaluated the health effects of Roux-en-Y gastric bypass in a cohort of adolescents (161 patients enrolled from 2006 through 2012) and a cohort of adults (396 patients enrolled from 2006 through 2009). The two cohorts were participants in two related but independent studies. Linear mixed and Poisson mixed models were used to compare outcomes with regard to weight and coexisting conditions between the cohorts 5 years after surgery. The rates of death and subsequent abdominal operations and selected micronutrient levels (up to 2 years after surgery) were also compared between the cohorts.

RESULTS

There was no significant difference in percent weight change between adolescents (-26%; 95% confidence interval [CI], -29 to -23) and adults (-29%; 95% CI, -31 to -27) 5 years after surgery (P = 0.08). After surgery, adolescents were significantly more likely than adults to have remission of type 2 diabetes (86% vs. 53%; risk ratio, 1.27; 95% CI, 1.03 to 1.57) and of hypertension (68% vs. 41%; risk ratio, 1.51; 95% CI, 1.21 to 1.88). Three adolescents (1.9%) and seven adults (1.8%) died in the 5 years after surgery. The rate of abdominal reoperations was significantly higher among adolescents than among adults (19 vs. 10 reoperations per 500 person-years, P = 0.003). More adolescents than adults had low ferritin levels (72 of 132 patients [48%] vs. 54 of 179 patients [29%], P = 0.004).

CONCLUSIONS

Adolescents and adults who underwent gastric bypass had marked weight loss that was similar in magnitude 5 years after surgery. Adolescents had remission of diabetes and hypertension more often than adults. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases; ClinicalTrials.gov number, NCT00474318.).

Association of Obesity Subtypes in the Longitudinal Assessment of Bariatric Surgery Study and 3-Year Postoperative Weight Change

OBJECTIVE

The study objective was to empirically identify subgroups of patients with obesity and investigate their association with postoperative weight change.

METHODS

A longitudinal analysis of 2,458 adults in the Longitudinal Assessment of Bariatric Surgery (LABS) study was used. Baseline data were used to identify subgroups. The outcome was 3-year weight change after bariatric surgery.

RESULTS

We identified four classes (subtypes) of obesity, which could be characterized as diabetes with low rates of high-density lipoprotein (Class 1), disordered eating (Class 2), mixed (Class 3), and extreme obesity with early onset (Class 4). Approximately 98% of participants in Class 1 had diabetes compared with < 40% in the other classes. There were high rates of binge eating in Class 2, and more than 92% of those in this class reported eating when not hungry. Class 4 was characterized by a higher BMI at baseline. Adults in Class 4 lost an average of 25.0% (males) and 30.3% (females) of their baseline weight over 3 years. In contrast with participants in Class 1, those in Classes 2 and 3 had significantly larger 3-year weight losses than their peers in Class 4.

CONCLUSIONS

Obesity is a heterogeneous disease. Bariatric surgery may be most beneficial for adults with disordered eating.

The use of low-calorie sweeteners is associated with self-reported prior intent to lose weight in a representative sample of US adults

BACKGROUND

Low-calorie sweeteners (LCSs) are said to be a risk factor for obesity and diabetes. Reverse causality may be an alternative explanation.

METHODS

Data on LCS use, from a single 24-h dietary recall, for a representative sample of 22 231 adults were obtained from 5 cycles of the National Health and Nutrition Examination Survey (1999-2008 NHANES). Retrospective data on intent to lose or maintain weight during the prior 12-months and 10-year weight history were obtained from the weight history questionnaire. Objectively measured heights and weights were obtained from the examination. Primary analyses evaluated the association between intent to lose/maintain weight and use of LCSs and specific LCS product types using survey-weighted generalized linear models. We further evaluated whether body mass index (BMI) may mediate the association between weight loss intent and use of LCSs. The association between 10-year weight history and current LCS use was evaluated using restricted cubic splines.

RESULTS

In cross-sectional analyses, LCS use was associated with a higher prevalence of obesity and diabetes. Adults who tried to lose weight during the previous 12 months were more likely to consume LCS beverages (prevalence ratio=1.64, 95% confidence interval (CI) 1.54-1.75), tabletop LCS (prevalence ratio=1.68, 95% CI 1.47-1.91) and LCS foods (prevalence ratio=1.93, 95% CI 1.60-2.33) as compared with those who did not. In mediation analyses, BMI only partially mediated the association between weight control history and the use of LCS beverages, tabletop LCS, but not LCS foods. Current LCS use was further associated with a history of prior weight change (for example, weight loss and gain).

CONCLUSIONS

LCS use was associated with self-reported intent to lose weight during the previous 12 months. This association was only partially mediated by differences in BMI. Any inference of causality between attempts at weight control and LCS use is tempered by the cross-sectional nature of these data and retrospective self-reports of prior weight loss/maintenance intent.

Adolescent weight history and adult cognition: before and after bariatric surgery

BACKGROUND

Cognitive deficits occur in a subset of individuals with obesity. Deficits can be reversed with bariatric surgery, though cognitive recovery is not equally exhibited across patients. Recent work has found that obesity during adolescence portends medical complications in adulthood; it is unknown if obesity in adolescence predicts adult cognition or cognitive recovery after weight loss surgery.

OBJECTIVES

The present study examines the relationship between weight history and cognitive function in obese adults undergoing bariatric surgery.

SETTING

Academic medical centers with bariatric care services.

METHODS

Seventy-eight bariatric surgery patients (mean age = 43.2 years) enrolled in an ancillary study to the Longitudinal Assessment of Bariatric Surgery (LABS) project completed a questionnaire recalling weight history at age 18. Cognitive testing was completed preoperatively and at 12-month follow-up.

RESULTS

Weight status at age 18 was linked to performance in several aspects of cognition. Higher body mass index at age 18 predicted poorer preoperative verbal fluency (B = -.26, P = .045) as well as postoperative cognitive recovery in attention (B = -.30, P = .01) at 12-month follow-up.

CONCLUSION

Higher body mass index at age 18 predicts verbal fluency performance in adults with obesity, as well as postoperative recovery of attention after bariatric surgery. The mechanisms underlying this connection are not fully clear, though findings may reflect effects of obesity on the brain during a crucial period of neural maturation or duration of obesity and cumulative impact of co-morbidities on cognition. Future work examining possible causal factors involved in these relationships is needed.

The effect of obesity in adolescence on adult health status

OBJECTIVE

To test the hypothesis that adolescent obesity would be associated with greater risks of adverse health in severely obese adults.

METHODS

Before weight loss surgery, adult participants in the Longitudinal Assessment of Bariatric Surgery-2 underwent detailed anthropometric and comorbidity assessment. Weight status at age 18 was retrospectively determined. Participants who were ≥80% certain of recalled height and weight at age 18 (1502 of 2308) were included. Log binomial regression was used to evaluate whether weight status at age 18 was independently associated with risk of comorbid conditions at time of surgery controlling for potential confounders.

RESULTS

Median age and adult body mass index (BMI) were 47 years and 46, respectively. At age 18, 42% of subjects were healthy weight, 29% overweight, 16% class 1 obese, and 13% class ≥2 obese. Compared with healthy weight at age 18, class ≥2 obesity at age 18 independently increased the risk of lower-extremity venous edema with skin manifestations by 435% (P < .0001), severe walking limitation by 321% (P < .0001), abnormal kidney function by 302% (P < .0001), polycystic ovary syndrome by 74% (P = .03), asthma by 48% (P = .01), diabetes by 42% (P < .01), obstructive sleep apnea by 25% (P < .01), and hypertension (by varying degrees based on age and gender). Conversely, the associated risk of hyperlipidemia was reduced by 61% (P < .01).

CONCLUSIONS

Severe obesity at age 18 was independently associated with increased risk of several comorbid conditions in adults undergoing bariatric surgery.