Social and spatial heterogeneity in psychosis proneness in a multilevel case-prodrome-control study

OBJECTIVE

To test whether spatial and social neighbourhood patterning of people at ultra-high risk (UHR) of psychosis differs from first-episode psychosis (FEP) participants or controls and to determine whether exposure to different social environments is evident before disorder onset.

METHOD

We tested differences in the spatial distributions of representative samples of FEP, UHR and control participants and fitted two-level multinomial logistic regression models, adjusted for individual-level covariates, to examine group differences in neighbourhood-level characteristics.

RESULTS

The spatial distribution of controls (n = 41) differed from UHR (n = 48; P = 0.04) and FEP participants (n = 159; P = 0.01), whose distribution was similar (P = 0.17). Risk in FEP and UHR groups was associated with the same neighbourhood-level exposures: proportion of single-parent households [FEP adjusted odds ratio (aOR): 1.56 95% CI: 1.00-2.45; UHR aOR: 1.59; 95% CI: 0.99-2.57], ethnic diversity (FEP aOR: 1.27; 95% CI: 1.02-1.58; UHR aOR: 1.28; 95% CI: 1.00-1.63) and multiple deprivation (FEP aOR: 0.88; 95% CI: 0.78-1.00; UHR aOR: 0.86; 95% CI: 0.76-0.99).

CONCLUSION

Similar neighbourhood-level exposures predicted UHR and FEP risk, whose residential patterning was closer to each other's than controls. Adverse social environments are associated with psychosis before FEP onset.

Clinical and sociodemographic comparison of people at high-risk for psychosis and with first-episode psychosis

OBJECTIVE

To compare clinical and sociodemographic characteristics previously associated with psychosis, between individuals at high-risk for psychosis (HR) and patients experiencing a first episode psychosis (FEP), to achieve a better understanding of factors associated with psychosis.

METHOD

Cross-sectional comparison of 30 individuals at HR with 30 age-gender matched FEP, presenting to an early intervention service for psychosis. Participants were followed-up for 2 years to establish the proportion of HR who made the transition into FEP.

RESULTS

Both groups showed similar socio-clinical characteristics, including immigration status, employment history, marital status, family history of psychotic illness, self-harm and alcohol and drug use. The HR group had a lower level of education, higher burden of trauma, earlier onset of psychiatric symptoms and a longer delay in accessing specialised services. A younger onset of symptoms was associated with a longer delay in accessing services in both groups. After a 2 year follow-up, only three (10%) of the HR group made a transition into FEP.

CONCLUSION

The similarities observed between individuals at HR and those with FEP suggest that known variables associated with psychosis may be equally prevalent in people at HR who do not develop a psychotic disorder.

Spread of Mycobacterium tuberculosis in a community implementing recommended elements of tuberculosis control

CONTEXT

Despite improvements in tuberculosis (TB) control during the past decade, Mycobacterium tuberculosis transmission and resulting disease continue to occur in the United States.

OBJECTIVE

To determine the primary reasons for disease development from a particular strain of M tuberculosis.

DESIGN

Population-based, molecular epidemiological study.

SETTING

Urban community in the San Francisco Bay area of California with recommended elements of TB control in place.

PATIENTS

Seventy-three TB cases were reported in 1996-1997 that resulted from 1 strain of M tuberculosis as identified by TB genotyping and epidemiological linkage.

MAIN OUTCOME MEASURES

Transmission patterns involving source and secondary case-patients; primary reasons for disease development.

RESULTS

Seventy-three (33%) of 221 TB case-patients in this community resulted from this strain of M tuberculosis. Thirty-nine (53%) of the 73 case-patients developed TB because they were not identified as contacts of source case-patients; 20 case-patients (27%) developed TB because of delayed diagnosis of their sources; and 13 case-patients (18%) developed TB because of problems associated with the evaluation or treatment of contacts; and 1 case-patient (1%) developed TB because of delay in being elicited as a contact. Of the 51 TB cases identified with sources, 49 (96%) were infected within the 2 years prior to diagnosis.

CONCLUSIONS

Our results indicate that in a community that has implemented the essential elements of TB control, TB from ongoing transmission of M tuberculosis will continue to develop unless patients are diagnosed earlier and contacts are more completely identified. JAMA. 2000.

Dissemination of Mycobacterium tuberculosis across the San Francisco Bay Area

The propensity of Mycobacterium tuberculosis genotypes to spread across geographic boundaries was investigated by comparing the IS6110 and polymorphic GC-rich sequence patterns of M. tuberculosis isolates from San Francisco and the East Bay, two distinct regions separated by San Francisco Bay. Of 724 isolates from incident tuberculosis patients during 1992 and 1993, only 53 (7.3%) had patterns matching > or = 1 isolates from the other region. In the multivariable analysis of patient risk factors, an AIDS diagnosis (odds ratio [OR], 1.89; 95% confidence interval [CI], 1.00-3.57) and non-Asian race (OR, 3.43; 95% CI, 1.59-7.42) were associated with having an isolate with a matching pattern. Of 375 unique IS6110 patterns among San Francisco isolates, only 9 (2.4%) matched patterns of East Bay isolates. These population-based data suggest that in the San Francisco Bay Area, M. tuberculosis does not rapidly spread across geographic boundaries, and tuberculosis control efforts should focus on transmission within defined areas.

Discrepancies in tuberculin skin test results with two commercial products in a population of intravenous drug users

Screening for tuberculosis (using the Mantoux test) and human immunodeficiency virus (HIV) was conducted among intravenous drug users (IVDUs) recruited from a San Francisco Bay Area neighborhood. Of 178 IVDUs skin-tested with one commercial purified protein derivative (PPD) preparation, a reaction of > or = 5 mm of induration occurred in 62 (47%) of 133 HIV-negative and 13 (29%) of 45 HIV-positive IVDUs (P = .037). Forty-two IVDUs with an initial PPD reaction > or = 5 mm were retested with a second commercial preparation; 11 (26%) had no reaction (0 mm) on retesting. These 11 were 5 (56%) of 9 HIV-positive and 6 (18%) of 33 HIV-negative persons (P = .038). These discrepancies may be unique to specific lots of product or may reflect more general differences. A degree of caution in evaluating unexpected tuberculin skin test results may be indicated. Response to different tuberculin products by HIV status should be further evaluated.