Estimate Group Differences Research Articles

Schizophrenia and the incidence of cardiovascular morbidity: A population-based longitudinal study in Ontario, Canada

ObjectiveDespite the high rates of cardiovascular mortality among people with schizophrenia, little is known about the incidence of cardiovascular morbidity in this population. We assessed whether individuals diagnosed with schizophrenia, in comparison to a population-proxy comparison group (comprised of individuals receiving an appendicitis-related primary diagnosis), would have a significantly greater risk of subsequent readmission to an inpatient or Emergency Department setting with a cardiovascular condition. DesignUsing inpatient hospital discharge records from April 1, 2002 to March 31, 2006 in Ontario, Canada, we constructed a population-based cohort study of patients who were followed for a period up to 4 years. Individuals with a primary ICD-10 (F20) schizophrenia diagnosis (n=9815) were matched with persons with a primary ICD-10 appendicitis-related diagnosis (K35-37) on sex, age, average neighbourhood income level, and amount of follow-up time available. We used a Cox regression procedure to estimate group differences in time-to-readmission with a cardiovascular-related diagnosis. ResultsIndividuals in the Schizophrenia group had a significantly greater adjusted risk of readmission for a cardiovascular event in comparison to individuals in the Appendicitis group [adjusted hazard ratio (AHR)=1.43, 95% CI, 1.22–1.69]. ConclusionsGiven the elevated risk of cardiovascular morbidity among individuals with schizophrenia, our findings add to the importance of screening and intervention programs for metabolic disorders and known cardiovascular risk factors among patients with schizophrenia.

The incidence of cardiovascular morbidity among patients with bipolar disorder: A population-based longitudinal study in Ontario, Canada

Background Despite the high rates of cardiovascular risk factors among people with bipolar disorder, little is known about the incidence of cardiovascular morbidity in this population. Methods Based upon Ontario, Canada hospital discharge records from April 1, 2002 to March 31, 2006, we constructed a population-based cohort study to assess whether individuals diagnosed with bipolar disorder ( n = 5999) would have a significantly greater risk of subsequent readmission with a cardiovascular condition in comparison to a matched population-proxy group of individuals receiving an appendicitis primary diagnosis. A Cox regression procedure was used to estimate group differences in time-to-readmission with a cardiovascular-related diagnosis. Patients were followed for a period up to 4 years. Results The bipolar disorder group had a significantly greater adjusted risk of readmission for a cardiovascular event in comparison to individuals in the appendicitis group [adjusted hazard ratio (AHR) = 1.66, 95% CI, 1.37–2.07, p < 0.001). Limitations Current research has not confirmed the accuracy of ICD-10 bipolar diagnoses in population-based administrative files with a gold-standard diagnostic reference. Also, our study did not have access to mortality files which, given the elevated rate of mortality among patients with bipolar disorder, may have led to an underestimation of link between bipolar disorder and cardiovascular morbidity. Conclusions In light of the elevated risk of cardiovascular morbidity among persons with bipolar disorder, our findings add to the importance of screening and intervention programs for metabolic disorders and known cardiovascular risk factors among patients with bipolar disorder.

Acid-Base Effects of a Bicarbonate-Balanced Priming Fluid during Cardiopulmonary Bypass: Comparison with Plasma-Lyte 148. A Randomised Single-Blinded Study

Fluid-induced metabolic acidosis can be harmful and can complicate cardiopulmonary bypass. In an attempt to prevent this disturbance, we designed a bicarbonate-based crystalloid circuit prime balanced on physico-chemical principles with a strong ion difference of 24 mEq/l and compared its acid-base effects with those of Plasma-Lyte 148, a multiple electrolyte replacement solution containing acetate plus gluconate totalling 50 mEq/l. Twenty patients with normal acid-base status undergoing elective cardiac surgery were randomised 1:1 to a 2 litre prime of either bicarbonate-balanced fluid or Plasma-Lyte 148. With the trial fluid, metabolic acid-base status was normal following bypass initiation (standard base excess 0.1 (1.3) mEq/l, mean, SD), whereas Plasma-Lyte 148 produced a slight metabolic acidosis (standard base excess -2.2 (2.1) mEq/l). Estimated group difference after baseline adjustment was 3.6 mEq/l (95% confidence interval 2.1 to 5.1 mEq/l, P=0.0001). By late bypass, mean standard base excess in both groups was normal (0.8 (2.2) mEq/l vs. -0.8 (1.3) mEq/l, P=0.5). Strong ion gap values were unaltered with the trial fluid, but with Plasma-Lyte 148 increased significantly on bypass initiation (15.2 (2.5) mEq/l vs. 2.5 (1.5) mEq/l, P < 0.0001), remaining elevated in late bypass (8.4 (3.4) mEq/l vs. 5.8 (2.4) mEq/l, P < 0.05). We conclude that a bicarbonate-based crystalloid with a strong ion difference of 24 mEq/l is balanced for cardiopulmonary bypass in patients with normal acid-base status, whereas Plasma-Lyte 148 triggers a surge of unmeasured anions, persisting throughout bypass. These are likely to be gluconate and/or acetate. Whether surges of exogenous anions during bypass can be harmful requires further study.

Measurement invariance: Review of practice and implications

A review of efforts to assess the invariance of measurement instruments across different respondent groups using confirmatory factor analysis (CFA) is provided for the years since the Vandenberg and Lance [Vandenberg, R. J., & Lance, C. E. (2000). A review and synthesis of the measurement invariance literature: Suggestions, practices, and recommendations for organizational research. Organizational Research Methods, 3, 4–69.] review. Investigators are more frequently reporting tests of scalar invariance and tests for differences in latent factor means and partial invariance. Efforts have been made to assess, the impact of the choice of a referent indicator in multi-group studies, the appropriateness of forming partials as indicators of a latent construct, the degree of convergence of item response theory and CFA analyses of measurement differences across groups, and the implications of findings of invariance. In this context, a demonstration of the impact of partial invariance on estimated group differences in reliability and means is provided and discussed.

Body fat distribution in stunted compared with normal-height children from the shantytowns of São Paulo, Brazil

Objective The objective of this study was to determine whether central fat distribution varies between children who were growth retarded as young children and normal-height children from the same impoverished communities of São Paulo, Brazil. Methods A prospective study of 50 stunted and normal-height children in São Paulo, Brazil was conducted in which children were measured for changes in fat mass (FM) and fat distribution (using dual-energy X-ray absorptiometry and anthropometry) and Tanner stage over a 4-y period. Statistical analyses included multiple linear regression to control for confounding factors and Student’s t test was used to estimate group differences. Results At follow-up, stunted children were shorter, weighed less, and had less total FM compared with control children. There were no differences between the two groups with respect to percent FM or percent truncal FM (%TrFM). Linear regression analyses were used to determine that stunted children had 1) increased TrFM (independent of FM); 2) increased %TrFM (independent of FM, gender, and Tanner stage), and 3) a borderline significantly greater change in TrFM (independent of FM, gender, and Tanner stage). Conclusion Stunted children are more likely to deposit fat centrally when entering puberty, a significant risk factor for chronic diseases. Our results may explain part of the association between early growth retardation and later risk for metabolic diseases.

Transforming Growth Factor-β and Urokinase Plasminogen Activator Presents at Endothelial Cell-Pericyte Interdigitation in Human Granulation Tissue

Previous studies suggest that amygdala volume, when compared with healthy controls, is increased in young children with autism, is unchanged in cohorts of older youth, and is smaller in adults. Hippocampal volume, however, does not appear to have age-related changes, and it is unclear whether individuals with autism have volumetric differences in this structure. The goal of this pilot investigation is to characterize the developmental trajectories of the amygdala and hippocampus in children with autism between the ages of 8 and 14 years and to examine clinical correlates of volume change.Twenty-three children with autism and 23 controls between the ages of 8 and 12 underwent a magnetic resonance imaging procedure of the brain (T1-weighted) at two time points. Nine children with autism and 14 controls had good quality scans from both time points; however, all usable scans from all subjects (15 children with autism and 22 controls) were included in a mixed effect analysis. Regression models were used to estimate group differences in amygdala and hippocampal volumes. Changes in amygdala and hippocampal volumes (Time 2 − Time 1) were correlated with clinical severity measures.Amygdala volume changes with time were similar between the two groups. Within the autism group, right amygdala volume change was correlated with the ability to establish appropriate eye contact. Right hippocampal volume was significantly increased in the autism group when compared with controls. Differences in right hippocampal volume change with time between the two groups approached significance.This study provides preliminary evidence of normalization of amygdala volumes in late childhood and adolescence. It also suggests that hippocampal volumetric differences may exist in autism in late childhood and adolescence.

A longitudinal evaluation of prevalent negative beliefs about residential placement for troubled adolescents.

To investigate the validity of five prevalent negative beliefs about residential placement, we followed adolescents from a residential program and a comparison group at 3-month intervals for 4 to 8 years. This residential program in the Midwest uses the Teaching-Family Model in which six to eight adolescents live in a family-style environment. The interviews included five scales reflecting youths' views about important aspects of their lives in placement: (1) Delivery of Helpful Treatment, (2) Satisfaction with Supervising Adults, (3) Isolation from Family, (4) Isolation from Friends, and (5) Sense of Personal Control. Hierarchical linear modeling allowed us to estimate group differences while controlling for developmental trends, demographic factors, and prior differences between groups. The two groups were equivalent on all scales before the study. During the following placement, however, the treatment group's ratings were significantly more positive than the comparison group on four of the five scales and approached significance on the fifth. These findings suggest that negative beliefs about life in residential placement for adolescents may not apply to all programs.