Weight Gain Trajectory and Pain Interference in Young Adulthood: Evidence from a Longitudinal Birth Cohort Study.

OBJECTIVE: Obesity is associated with chronic pain, but the contribution of body mass index (BMI) trajectories over the life course to the onset of pain problems remains unclear. We retrospectively analyzed how BMI trajectories during the transition to adulthood were associated with a measure of pain interference obtained at age 29 in a longitudinal birth cohort study. METHODS: Data from the National Longitudinal Survey of Youth, 1997 Cohort (follow-up from 1997 to 2015), were used to determine BMI trajectories from age 14 to 29 via group trajectory modeling. At age 29, respondents described whether pain interfered with their work inside and outside the home over the past four weeks (not at all, a little, or a lot). Multivariable ordinal logistic regression was used to evaluate pain interference according to BMI trajectory and study covariates. RESULTS: Among 7,875 respondents, 11% reported "a little" and 4% reported "a lot" of pain interference at age 29. Four BMI trajectory groups were identified, varying in starting BMI and rate of weight gain. The "obese" group (8% of respondents) had a starting BMI of 30 kg/m2 and gained an average of 0.7 kg/m2/y. On multivariable analysis, this group was the most likely to have greater pain interference, compared with "high normal weight" (odds ratio [OR] = 1.47, 95% confidence interval [CI] = 1.14-1.88), "low normal weight" (OR = 1.45, 95% CI = 1.13-1.87), and "overweight" trajectories (OR = 1.33, 95% CI = 1.02-1.73). CONCLUSIONS: Obesity and rapid weight gain during the transition to adulthood were associated with higher risk of pain interference among young adults.

Does more education cause lower BMI, or do lower-BMI individuals become more educated? Evidence from the National Longitudinal Survey of Youth 1979.

More educated adults have lower average body mass index (BMI). This may be due to selection, if adolescents with lower BMI attain higher levels of education, or it may be due to causation, if higher educational attainment reduces BMI gain in adulthood. We test for selection and causation in the National Longitudinal Survey of Youth 1979, which has followed a representative US cohort from age 14-22 in 1979 through age 47-55 in 2012. Using ordinal logistic regression, we test the selection hypothesis that overweight and obese adolescents were less likely to earn high school diplomas and bachelor's degrees. Then, controlling for selection with individual fixed effects, we estimate the causal effect of degree completion on BMI and obesity status. Among 18-year-old women, but not among men, being overweight or obese predicts lower odds of attaining higher levels of education. At age 47-48, higher education is associated with lower BMI, but 70-90% of the association is due to selection. Net of selection, a bachelor's degree predicts less than a 1 kg reduction in body weight, and a high school credential does not reduce BMI.

Birth Weight and Early Cognitive Skills: Can Parenting Offset the Link?

Objectives There is an enduring negative association between low birth weight (<2500 g) and early childhood cognitive skills. This study examines if parenting practices meaningfully contribute to or offset birth weight disparities in cognitive development prior to formal schooling. Methods This study uses the ECLS-B, a nationally representative sample of live births in the United States in 2001. Unlike studies focused on one or two measures of parenting and investment, this study considers a wide array parenting measures collected at multiple time points, tracked from before birth across 5 years of development. Results Regression results show that nearly 50 % of the low-birth-weight gap in early math and reading ability is associated with family socioeconomic status. Between-family OLS regressions show that parenting practices, including "parental interaction," "cognitive stimulation," and "parent quality", are negatively associated with low birth weight and positively associated with improved cognitive skill among all children. After adjustment for family socioeconomic status, parenting practices did little to offset (by mediation or moderation) remaining birth weight disparities in early cognitive development. Conclusions Effective parenting is positively associated with cognitive development, but parenting is not a panacea-the developmental disadvantages associated with poor child health are not linked to parenting practices. We argue that birth weight disparities are rooted in biology and cannot easily be offset by parenting practices.

An education gradient in health, a health gradient in education, or a confounded gradient in both?

There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated. This is partly because adolescent SRH is associated with early advantages including adolescents' academic performance, college plans, and family background (confounding); however, net of these confounders adolescent SRH still predicts adult educational attainment (selection). Fixed-effects longitudinal regression shows that educational attainment has little causal effect on SRH at age 31. Completion of a high school diploma or associate's degree has no effect on SRH, while completion of a bachelor's or graduate degree have effects that, though significant, are quite small (less than 0.1 points on a 5-point scale). While it is possible that educational attainment would have greater effect on health at older ages, at age 31 what we see is a health gradient in education, shaped primarily by selection and confounding rather than by a causal effect of education on health.

Health consequences of same and opposite-sex unions: partnership, parenthood, and cardiovascular risk among young adults.

We use the National Longitudinal Survey of Adolescent to Adult Health to examine union and parenthood differences across same and opposite-sex couples in systolic and diastolic blood pressure (SBP and DBP), C-reactive protein (CRP), and abdominal adiposity (waist circumference) among partnered (dating, cohabiting, married) young adults ages 25-33. Relative to women dating men, women cohabiting with women reported lower DBP and were less likely to have high CRP. Mothers reported lower SBP and DBP than non-mothers, but were more likely to have high waist circumference if they lived with a biological or step-child. Among men, nonresidential fathers reported higher DBP than nonfathers, and married men were more likely to have high waist circumference than men dating an opposite-sex partner. Same-sex cohabitation was neither a risk factor nor a health resource for men. Although the sample sizes for same-sex couples are quite small compared with those for opposite-sex couples, this study provides initial insight that occupying a sexual minority status while partnered is associated with some health benefits and few or no health risks relative to those who are dating an opposite sex partner.

Why are educated adults slim-Causation or selection?

More educated adults tend to have lower body mass index (BMI) and a lower risk of overweight and obesity. We contrast two explanations for this education gradient in BMI. One explanation is selection: adolescents with high BMI are less likely to plan for, attend, and complete higher levels of education. An alternative explanation is causation: higher education confers lifelong social, economic, and psychological benefits that help adults to restrain BMI growth. We test the relative importance of selection and causation using data from the National Longitudinal Survey of Youth, 1997 cohort (NLSY97), which tracks self-reported BMI from adolescence (age 15) through young adulthood (age 29). Ordinal regression models confirm the selection hypothesis that high-BMI adolescents are less likely to complete higher levels of education. Selection has primarily to do with the fact that high-BMI adolescents tend to come from socioeconomically disadvantaged families and tend to have low grades and test scores. Among high-BMI girls there is also some evidence that educational attainment is limited by bullying, poor health, and early pregnancy. About half the selection of high-BMI girls out of higher education remains unexplained. Fixed-effects models control for selection and suggest that the causal effect of education on BMI, though significant, accounts for only one-quarter of the mean BMI differences between more and less educated adults at age 29. Among young adults, it appears that most of the education gradient in BMI is due to selection.

Housework: Cause and consequence of gender ideology?

Nearly all quantitative studies examining the association between the division of housework and gender ideology have found that gender egalitarianism results in less housework for wives, more for husbands, and more equal sharing of housework by couples. However, a few studies suggest housework has a nontrivial influence on gender ideology. An overreliance on single-direction, single-equation regression models and cross-sectional data has limited past research from making strong claims about the causal relationship between gender ideology and housework. We use data on married couples from Waves 1 and 2 of the National Survey of Families and Households and nonrecursive simultaneous equation models to assess the causal relationship between housework and gender ideology. Results show a mutual and reciprocal relationship between the division of housework and gender ideology for both husbands' and wives'. Reciprocity is strongest for husbands while for wives the relationship is partially indirect and mediated through their husbands' gender ideologies.

The GraftLink ulnar collateral ligament reconstruction: biomechanical comparison with the docking technique in both kinematics and failure tests.

BACKGROUND: Ulnar collateral ligament (UCL) reconstruction aims to restore valgus stability, and numerous techniques have been described in the literature. HYPOTHESIS/ PURPOSE: To biomechanically compare the GraftLink (GL) technique with traditional bone tunnels used in the docking (DO) technique. It is hypothesized that the GL method will offer a stiffer, less lax construct compared with the DO. STUDY DESIGN: Controlled laboratory study. METHODS: Native and reconstructed states were tested in 7 matched pairs of cadaveric arms. To test kinematics, a 1.5-N·m valgus torque was applied and the resultant displacement at 15° to 90° of flexion was measured. Dissipated energy and the torque at the peak of the 10th cycle of preconditioning were analyzed during kinematic tests. Failure testing was performed by internal rotation of the humerus at 4.5 deg/s in 70° of flexion. Ulnotrochlear joint (UTJ) gapping was quantified during failure tests by use of video tracking. RESULTS: Kinematics testing revealed no differences between the native state and the reconstructed state in either the DO or the GL group at any flexion angle. Stiffness was lower in the reconstructed specimens in both the DO (39.92 N·m/rad) and GL (50.74 N·m/rad) groups compared with their matched native states (DO Native, 71.41 N·m/rad, P = .005; GL Native, 86.36 N·m/rad, P = .002). There was no difference in stiffness between DO and GL. Reconstructed specimens in the GL group had lower torque at failure compared with native specimens (17.404 N·m vs 24.63 N·m, P = .038), but there was no difference in the DO group at failure. There was no difference in torque at failure between DO and GL. The DO exhibited higher angular displacement at failure compared with the native state (34.21° vs 21.79°, P = .010) and compared with the GL when normalized (1.58-fold vs 1.19-fold, P = .039). Compared with their native states, both DO and GL had significantly higher UTJ gapping at 3 N·m and at failure. The DO had significantly higher normalized UTJ gapping than the GL at 3 N·m (P = .037) and at failure (P = .043). CONCLUSION: The DO and GL both restored joint kinematics under low loading conditions. Although less stiff, the GL exhibited lower joint gapping and laxity than did the DO. CLINICAL RELEVANCE: Understanding the biomechanics of UCL reconstruction has significant implications for postoperative management as it relates to early rehabilitation. Biomechanically inferior constructs could risk graft failure or early loosening during rehabilitation, and comparing the biomechanics of new techniques to established, widely used procedures such as the docking technique can provide important information about the immediate postoperative performance.

Biomechanical evaluation of the TightRope versus traditional docking ulnar collateral ligament reconstruction technique: kinematic and failure testing.

BACKGROUND: Numerous variations of ulnar collateral ligament (UCL) reconstruction have been described since the original technique by Jobe et al. Purpose/ HYPOTHESIS: To biomechanically compare the new TightRope technique and the traditional ulnar bone tunnels as used in the docking technique. The hypothesis was that the TightRope technique would exhibit improved kinematics and comparable failure properties. STUDY DESIGN: Controlled laboratory study. METHODS: Seven matched pairs of cadaveric arms (mean age, 44.71 years) were tested in both the native state and reconstructed state. Kinematics were assessed at 15° to 90° of flexion by applying a 1.5-N·m valgus torque and measuring the resultant angular displacement. Failure testing was performed by loading to failure at 4.5 deg/s in 70° of flexion. Sides of a matched pair were randomized to the TightRope (TR) and docking (DO) techniques after testing the native state. RESULTS: There was no significant difference in kinematic results between the native state and reconstructed state in either the TR or DO group at 15° to 75° of flexion. At 90°, the TR group had significantly higher angular displacement (2.23° ± 1.0°) compared with the native state (1.31° ± 0.7°) (P = .020). The TR-reconstructed specimens had significantly lower initial stiffness (49.34 ± 19.3 N·m/rad vs 82.47 ± 36.0 N·m/rad, respectively; P = .007) and total stiffness (53.81 ± 27.8 N·m/rad vs 101.06 ± 34.4 N·m/rad, respectively; P < .001) than did the paired native specimens. In addition, the TR-reconstructed specimens had significantly lower torsional torque at 5° of valgus rotation (mean, 4.61 ± 2.2 N·m vs 7.62 ± 3.7 N·m, respectively; P = .010), at 15° of valgus rotation (12.24 ± 4.4 N·m vs 20.65 ± 6.8 N·m, respectively; P = .002), and at ultimate failure (19.18 ± 7.5 N·m vs 25.42 ± 7.1 N·m, respectively; P = .025) than did the paired native specimens. There was no significant difference in torsional torque between the TR and DO groups at 5° of valgus rotation (4.61 ± 2.2 N·m vs 4.09 ± 1.7 N·m, respectively; P = .644), at 15° of valgus rotation (12.24 ± 4.4 N·m vs 17.94 ± 7.23 N·m, respectively; P = .178), or at failure (19.18 ± 7.5 N·m vs 23.19 ± 10.6 N·m, respectively; P = .444). The DO group exhibited significantly higher angular displacement at failure than did the native state (28.12° ± 8.5° vs 18.04° ± 4.8°, respectively; P = .009), but there was no difference at 3 N·m of loading. There was no significant difference in angular displacement either at 3 N·m or at failure between the native state and reconstructed state in the TR group. CONCLUSION: Both the TR and DO techniques restored native joint kinematics from 15° to 75° of flexion under low loading conditions. While the TR technique exhibited inferior failure torque compared with the native state, the DO technique did not differ from the native state. No differences were found between the TR and DO groups when compared directly. The DO technique restored valgus stability under high loading to a greater extent than did the TR technique but also failed at higher angular displacement. CLINICAL RELEVANCE: Strong postoperative UCL reconstruction fixation is important to restore ulnotrochlear joint stability. Our study demonstrates that the new TR technique has comparable kinematic and failure properties to the traditional DO technique.

Biomechanical comparison of 3 methods to repair pectoralis major ruptures.

BACKGROUND: Pectoralis major ruptures are closely associated with weight lifting and participation in sports. The anatomy of the pectoralis major tendon is unique with an elongated thin footprint requiring multiple points of fixation to restore the native anatomy. Multiple options exist for tendon repairs, but the strongest construct has yet to be identified. PURPOSE: The intent of this study was to compare the load to failure of bone trough, cortical button, and suture anchor repairs of the pectoralis major tendon in the extended and abducted position. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty fresh-frozen cadaveric shoulders were divided equally into 3 groups based on the repair technique to be performed. Bone mineral density of the surgical neck of the proximal humerus was assessed before each repair. Bone trough, suture anchor, and cortical button repairs were performed as dictated by computerized randomization. Each specimen was loaded to failure and mode of failure was noted. RESULTS: The majority of failures occurred through the suture used for tendon repair. One specimen in the bone trough group failed via fracture of the proximal humerus. The suture anchor group failed at the implant in 5 of 9 specimens and through the suture in 4 of 9 specimens. Load to failure was greatest in bone trough repairs at 596 N, followed by cortical button at 494 N, and finally suture anchor repairs with 383 N. Load to failure was significantly greater in the bone trough group when compared with suture anchor repairs (P = .007). No correlation was found between bone mineral density and load to failure. CONCLUSION: Bone trough repair of the pectoralis major tendon was stronger than suture anchor repair. CLINICAL RELEVANCE: Identification of the strongest repair may help guide surgical repair.

Infant health, race/ethnicity, and early educational outcomes using the ECLS-B.

Using data from the "Early Childhood Longitudinal Study­Birth Cohort," this article emphasizes the central role of poor infant health as a mechanism in the formation of early educational disparities. Results indicate that the varying prevalence of poor infant health across racial/ethnic groups explains a significant portion of the black disadvantage and a moderate portion of the Asian advantage relative to whites in math and reading skills at age four. Results also demonstrate that infant health is an equal opportunity offender across social groups as children with poor health are equally disadvantaged in terms of early cognitive development, regardless of racial/ethnic status. Overall, results indicate that health at birth has important consequences for individual educational achievement and racial/ethnic disparities in cognitive development and school readiness.