Confirmatory test of two factors and four subtypes of bipolar disorder based on lifetime psychiatric co-morbidity

BACKGROUND

The first aim was to use confirmatory factor analysis (CFA) to test a hypothesis that two factors (internalizing and externalizing) account for lifetime co-morbid DSM-IV diagnoses among adults with bipolar I (BPI) disorder. The second aim was to use confirmatory latent class analysis (CLCA) to test the hypothesis that four clinical subtypes are detectible: pure BPI; BPI plus internalizing disorders only; BPI plus externalizing disorders only; and BPI plus internalizing and externalizing disorders.

METHOD

A cohort of 699 multiplex BPI families was studied, ascertained and assessed (1998-2003) by the National Institute of Mental Health Genetics Initiative Bipolar Consortium: 1156 with BPI disorder (504 adult probands; 594 first-degree relatives; and 58 more distant relatives) and 563 first-degree relatives without BPI. Best-estimate consensus DSM-IV diagnoses were based on structured interviews, family history and medical records. MPLUS software was used for CFA and CLCA.

RESULTS

The two-factor CFA model fit the data very well, and could not be improved by adding or removing paths. The four-class CLCA model fit better than exploratory LCA models or post-hoc-modified CLCA models. The two factors and four classes were associated with distinctive clinical course and severity variables, adjusted for proband gender. Co-morbidity, especially more than one internalizing and/or externalizing disorder, was associated with a more severe and complicated course of illness. The four classes demonstrated significant familial aggregation, adjusted for gender and age of relatives.

CONCLUSIONS

The BPI two-factor and four-cluster hypotheses demonstrated substantial confirmatory support. These models may be useful for subtyping BPI disorders, predicting course of illness and refining the phenotype in genetic studies.

Do benefits and barriers differ by stage of adoption for colorectal cancer screening?

In 2003, over 148,300 people were expected to be diagnosed and 56,000 to die from colorectal cancer (CRC). First-degree relatives (FDRs) of people with colon cancer have a two- to eight-fold increased risk for CRC. Despite evidence that screening is effective, adherence with screening recommendations in this at-risk population is low. This study's purposes were to (1) identify perceived benefits and barriers of fecal occult blood testing (FOBT), sigmoidoscopy and colonoscopy, and (2) compare demographic characteristics and perceived benefits and barriers by stage of adoption for CRC screening. Participating FDRs (n = 257) completed a 40-min structured telephone interview. Despite high rates of agreement with the benefits of screening, most FDRs were not contemplating being screened. Of those 50 and older, most were in precontemplation for FOBT, sigmoidoscopy and colonoscopy. Older age was related to stage for FOBT and sigmoidoscopy, but not colonoscopy. Lack of provider recommendation also was related to stage. Consistent with theoretical predictions, precontemplators had (1) higher rates of endorsement of specific barriers to screening and (2) lower rates of endorsement of benefits than contemplators or actors. For morbidity and mortality reduction, participation in routine, periodic screening is imperative. These findings can guide development of screening-promoting interventions.