Strategies to Improve the Predictive Accuracy of Diagnostic Tests

An attempt to solve this problem is a multi-level procedure of case identification (sequential screening) [144]. If case identification is based, instead of on the general population, on a group of people who have already contacted a general practitioner, psychologist or a counselling service because of mental problems, the rates for false positive cases will drop considerably.

The Early Recognition Inventory (ERIraos), which we developed in the German Research Network on Schizophrenia, pursues a two-step strategy for the identification of at-risk persons. In the first step a screening procedure of a high sensitivity and slightly increased risk threshold is applied in general practices, counselling services or schools. In these populations at an increased risk, the ratio of risk persons to non-risk persons is far better in balance and the number of false positives much lower. The risk persons thus identified are referred to a specialist service or an early intervention centre where they will be examined by more differentiated instruments of the highest possible diagnostic and predictive power. In the efforts to validate such early recognition inventories, which have to be practical and economic to use and produce favourable results, biological tests may follow at a third level of risk identification. Designs of that type are being pursued in the Edinburgh high-risk study [89] and in a multicentre study in Germany [145].

An early recognition inventory successfully validated and fulfilling all the requirements mentioned is not yet available. To achieve an acceptable number needed to treat (NNT) and, hence, to meet the main economic and ethical requirements, risk predictions in early recognition instruments (state criteria) will be supplemented by ''longstanding biobehavioural markers'' [146]. The ones most frequently used are age of risk (e.g. up to 30 years), family history (at least one first-degree relative with schizophrenia), schizotypal personality and history of obstetric complications. An example of a set of risk criteria, which has been prospectively validated, was developed by Yung et al. [147,148] and Edwards and McGorry [74] with their operationalized concept of ultra-high risk (UHR) for psychosis. Included are the following trait factors [147]: age of risk 16 to 30 years, schizotypal personality or a first-degree relative with a history of psychotic disorder. As state indicators they chose attenuated psychotic symptoms or BLIPS and a change in mental state and functioning which results in a loss of 30 points or more in the Global Assessment of Functioning (GAF) scale for at least one month. Such a definition of an increased risk has considerable advantages in terms of diagnostic and prognostic power. Its weaknesses are the selective nature of risk assessment and that it does not include a rule for quantitative risk estimation.

BiPolar Explained

BiPolar Explained

Bipolar is a condition that wreaks havoc on those that it affects. If you suffer from Bipolar, chances are that your family suffers right with you. No matter if you are that family member trying to learn to cope or you are the person that has been diagnosed, there is hope out there.

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