An appropriate choice of controls in case/control studies of specific psychiatric disorders is crucial for valid risk-factor assessment. One suggested approach to control-group selection, the use of a well control group, is the focus of this paper. While using well controls has intuitive appeal, this paper shows that such a procedure can lead to ambiguous and biased results.

Investigation into the referral histories of a consecutive series of new patients attending two psychiatric out-patient clinics questioned the assumption that only the more severe and problematic cases are selected by general practitioners for specialist referral. In 40% of cases, clinical indications only became decisive in relation to emergent difficulties in managing the case, while 38% of patients or their relatives requested referral. The implications of these observations are considered in relation to alternative models of psychiatric intervention in the management of psychosocial disorders in primary care.

First, two examples of dichotomous logistic regression analysis are presented. The probability of being a psychiatric case according to the Present State Examination is predicted from the total score on the General Health Questionnaire and from the general practitioner's judgement on the presence of a mental health problem. Subjects were 292 primary care attenders. Results are compared with those from prior studies.

Next, the extension to the polytomous case is demonstrated. The probability of being at any given level of the Index of Definition (computed from PSE data) is estimated from the General Health Questionnaire total score by an ordered polytomous logistic regression model. Several applications of the polytomous logistic regression model are discussed. These range from estimating the proportion of psychiatric cases among individuals who refuse to be interviewed to the formulation of sampling schemes which can be expected to reduce costs while at the same time yielding optimal information for testing specific hypotheses.

The concept of ‘the pathway to psychiatric care’ as described by Goldberg & Huxley (1980) using a scheme of five ‘levels’ and four ‘filters’, has provided a useful framework in investigating referral processes in places where health services are organized in a way similar to the British National Health Service. Previous estimates of psychiatric morbidity at each of the levels of this model have been calculated, based upon data obtained from diverse geographical areas and over different time frames. The value of these estimates for service planning is therefore limited by the heterogeneity of the data sources. This paper provides data related to all five levels based upon the same geographical area (South-Verona, Italy) and within the same time frame (one week in 1987).

The importance of studying the full spectrum of psychiatric morbidity at all levels in the same area is discussed. In particular, it is shown that the assessment of morbidity in the primary medical care setting (levels 2 and 3) and data about filters 2 and 3 can provide useful information for the evaluation of specialist services (levels 4 and 5) as well as for understanding changes in the provision of specialist care.

The Mini-Mental State Examination was administered to 1865 general-practice patients aged 75 years and over. Even when demented cases were removed from analysis, respondents with relatively little education, together with those in social classes Ill-manual and below, were significantly more likely to score below the cut-off point used in North American community surveys to denote ‘cognitive impairment’. Education and social class influenced scores on all sections within the MMSE with the exception of registration. Sex influenced scores on tests of calculation and spelling backwards but had no effect on total scores. These findings emphasize the importance of investigating low scorers in more detail before making a diagnosis of dementia.

In order to carry out an epidemiological survey of child psychiatric disorders in a community sample, the Child Behaviour Checklist was chosen as a parental questionnaire for screening in the first stage of the study. A French version of this instrument was developed and a pilot study of the scale was completed on a clinical sample (N = 127). As a criterion to gauge its validity, the Rutter scale was used as a concurrent measure. The correlation coefficient between the total scores of the two scales is 0·79, and ranges between 0·22 and 0·96 for individual items. A linear regression analysis, using the total score of the Rutter scale as an independent variable, predicts a value of 41 as the optimal cut-off to be used for the Child Behaviour Checklist. Comparative properties (reliability and time of completion) of the two scales are presented and discussed.

The General Practice Research Unit (GPRU) was established at the Institute of Psychiatry in the late 1950s, under the honorary directorship of Professor Michael Shepherd. For 30 years it has been staffed by medically qualified workers and social scientists supported, at various times, by the Nuffield Foundation, the Mental Health Research Fund, and the Department of Health and Social Security, as well as by university monies.