A novel way to quantify schizophrenia symptoms in clinical trials.

BACKGROUND: A major problem in quantifying symptoms of schizophrenia is establishing a reliable distinction between enduring and dynamic aspects of psychopathology. This is critical for accurate diagnosis, monitoring and evaluating treatment effects in both clinical practice and trials. MATERIALS AND METHODS: We applied Generalizability Theory, a robust novel method to distinguish between dynamic and stable aspects of schizophrenia symptoms in the widely used Positive and Negative Symptom Scale (PANSS) using a longitudinal measurement design. The sample included 107 patients with chronic schizophrenia assessed using the PANSS at five time points over a 24-week period during a multi-site clinical trial of N-Acetylcysteine as an add-on to maintenance medication for the treatment of chronic schizophrenia. RESULTS: The original PANSS and its three subscales demonstrated good reliability and generalizability of scores (G = 0.77-0.93) across sample population and occasions making them suitable for assessment of psychosis risks and long-lasting change following a treatment, while subscales of the five-factor models appeared less reliable. The most enduring symptoms represented by the PANSS were poor attention, delusions, blunted affect and poor rapport. More dynamic symptoms with 40%-50% of variance explained by patient transient state including grandiosity, preoccupation, somatic concerns, guilt feeling and hallucinatory behaviour. CONCLUSIONS: Identified dynamic symptoms are more amendable to change and should be the primary target of interventions aiming at effectively treating schizophrenia. Separating out the dynamic symptoms would increase assay sensitivity in trials, reduce the signal to noise ratio and increase the potential to detect the effects of novel therapies in clinical trials.

Predictors of physical activity and quality of life in New Zealand prostate cancer survivors undergoing androgen-deprivation therapy.

AIMS: The aims of this study were to: quantify the levels and predictors of physical activity in prostate cancer survivors on androgen-deprivation therapy (ADT); gain some insight into the effect of physical activity on the quality of life of prostate cancer survivors on ADT; and compare the quality of life of prostate cancer survivors on ADT with matched controls. METHODS: A sample of 84 prostate cancer survivors on ADT were recruited from a register held by the Auckland District Health Board. Participants were mailed a collection of self-report surveys probing quality of life, physical activity and determinants of physical activity. RESULT: Less than half the prostate cancer sample were categorised as physically active, and there was no relationship between physical activity and age, PSA levels, or time on ADT. Compared to a matched control group the sample had lower scores for global quality of life, as well as on the physical and environmental quality of life domains. Results also showed that those prostate cancer survivors classified as active had higher levels of quality of life on average than those classified as insufficiently active. Attitude towards physical activity was the dominant predictor of the intention to be physically active, while perceived behavioural control was the dominant predictor of actual behaviour. CONCLUSIONS: Our findings describe a positive relationship between physical activity and quality of life in men with prostate cancer currently undergoing ADT. However, only half the sample was physically active, indicating that physical activity interventions aimed at prostate cancer survivors are of utility. Our data suggests targeting both attitudes and factors related to the ability to perform physical activity will be fruitful approaches.