The ZInEP Epidemiology Survey: background, design and methods

Abstract

This article introduces the design, sampling, field procedures and instruments used in the ZInEP Epidemiology Survey. This survey is one of six ZInEP projects (Zürcher Impulsprogramm zur nachhaltigen Entwicklung der Psychiatrie, i.e. the "Zurich Program for Sustainable Development of Mental Health Services"). It parallels the longitudinal Zurich Study with a sample comparable in age and gender, and with similar methodology, including identical instruments. Thus, it is aimed at assessing the change of prevalence rates of common mental disorders and the use of professional help and psychiatric sevices. Moreover, the current survey widens the spectrum of topics by including sociopsychiatric questionnaires on stigma, stress related biological measures such as load and cortisol levels, electroencephalographic (EEG) and near-infrared spectroscopy (NIRS) examinations with various paradigms, and sociophysiological tests. The structure of the ZInEP Epidemiology Survey entails four subprojects: a short telephone screening using the SCL-27 (n of nearly 10,000), a comprehensive face-to-face interview based on the SPIKE (Structured Psychopathological Interview and Rating of the Social Consequences for Epidemiology: the main instrument of the Zurich Study) with a stratified sample (n = 1500), tests in the Center for Neurophysiology and Sociophysiology (n = 227), and a prospective study with up to three follow-up interviews and further measures (n = 157). In sum, the four subprojects of the ZInEP Epidemiology Survey deliver a large interdisciplinary database.

Comparing two basic subtypes in OCD across three large community samples: a pure compulsive versus a mixed obsessive–compulsive subtype

“…Additional weights were introduced to account for nonresponse/ underrepresentation according to urbanicity status, education level, and the weight of any specific sex-birth year subgroup within the population of the 20-40 years old. The sampling and weighting procedures were described in detail by Ajdacic-Gross et al [2]. Additional analysis pooling all available individual data was performed in order to enlarge the statistical power of the findings derived from the three separate data sets.…”

“…Therefore, this discrepancy is probably a result of the instrument rather than explainable by factors such as regional differences between the PsyCoLaus sample and the Zurich Study and ZInEP sample, respectively. In contrast, the Zurich Study and the ZInEP study were parallelized with regard to basic methodological features (for more details see Ajdacic-Gross et al [2]) and showed more similarities. Second, while the basic findings distinguishing between PCS and the MOCS were consistent, the more detailed results depicted a relatively high degree of heterogeneity across the studies.…”

“…A stratified sample procedure was applied that included 60 % high scorers and 40 % low scorers (cutoff criterion 75th percentile of the GSI of the SCL-27 [31]) using a shortened version of the SPIKE (referred to as Mini-SPIKE) [6,9]. The detailed modifications of the SPIKE were recently described in detail by Ajdacic-Gross et al [2]. When asked for a face-to-face appointment, 64.9 % actually showed up.…”

Association between processing speed and subclinical psychotic symptoms in the general population: Focusing on sex differences

“…In the final step, 227 subjects from the two subsamples were randomly selected for laboratory testing and longitudinal surveys based on their prior consent to undergo additional testing (see Ajdacic-Gross et al, 2014). Those initially assigned to the psychosis subsample additionally completed the PD questionnaires and vice versa.…”

“…Thus participants were randomly assigned to either subgroup, which is why they did not differ in any characteristics besides the different questionnaires that they had to complete. A detailed rationale and description of the sampling procedure has been provided by Ajdacic-Gross et al (2014).…”