Cystic fibrosis-related diabetes (CFRD) and cognitive function in adults with cystic fibrosis.

BACKGROUND: Being able to function cognitively is imperative for successful achievement in school, working life, and disease self-management. Diabetes is known to cause changes in brain structure and long-term cognitive dysfunction. This work investigated cystic fibrosis-related diabetes (CFRD) as a mechanism for cognitive impairment in people with CF. It was hypothesised that cognition would be poorer in adults with CFRD than in those with CF without diabetes (CFND) or in healthy controls. METHODS: Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery which provides a comprehensive cognitive assessment with tests mapping onto specific brain regions. Demographic, clinical and self-reported health data were documented for all participants. CF specific clinical variables were recorded for the two CF groups. RESULTS: Ninety-eight people with CF (49CFRD,49CFND) and 49 healthy controls were recruited. People with CF demonstrated deficits in aspects of verbal and spatial memory, processing speed and cognitive flexibility compared with healthy controls, with all areas of the brain implicated. Those with CFRD had additional difficulties with higher-level processes known collectively as 'executive function', which demand greater cognitive load and recruit the prefrontal cortex. Compared with healthy controls, those with CFND and CFRD had an estimated 20% and up to 40% reduction in processing speed respectively. CONCLUSION: Managing CF requires higher order executive function. Impairments may be sufficient to interfere with self-care and the ability to perform everyday tasks efficiently. At which point in the CF disease trajectory these difficulties begin, and what may attenuate them, has yet to be determined.

Implementing the International Committee on Mental Health in Cystic Fibrosis (ICMH) guidelines: Screening accuracy and referral-treatment pathways.

BACKGROUND: The International Committee on Mental Health (ICMH) published screening guidelines in Cystic Fibrosis (CF). This work 1) evaluated the sensitivity of the recommended screening tools against the 'gold standard' clinical psychological assessment and 2) investigated referral and treatment pathways. METHODS: Ninety-six participants (79 caregivers; 17 adolescents with CF) completed the screening tools prior to formal assessment. Agreement between screening data and psychological assessment was evaluated, sensitivity analyses performed and referral pathways tracked. RESULTS: All participants with an elevated screen (moderate/severe range) were subsequently assessed as requiring treatment for major depression/anxiety disorders. However, many were referred for treatment without elevated scores. Hence, sensitivity was poor with the recommended threshold score of 10, but with a threshold of 5 the sensitivity was 76% for adults and 46% for adolescents. The area under the ROC curve (diagnostic test ability) was 0.89 for caregivers but lower at 0.68 for adolescents. CONCLUSION: Mental health screening is complex, particularly in adolescents. Nonetheless, it is a first valuable step to improve mental health care in CF. The need for psychological support is greater than anticipated by the TIDES study.

A reference relative time-scale as an alternative to chronological age for cohorts with long follow-up.

BACKGROUND: Epidemiologists have debated the appropriate time-scale for cohort survival studies; chronological age or time-on-study being two such time-scales. Importantly, assessment of risk factors may depend on the choice of time-scale. Recently, chronological or attained age has gained support but a case can be made for a 'reference relative time-scale' as an alternative which circumvents difficulties that arise with this and other scales. The reference relative time of an individual participant is the integral of a reference population hazard function between time of entry and time of exit of the individual. The objective here is to describe the reference relative time-scale, illustrate its use, make comparison with attained age by simulation and explain its relationship to modern and traditional epidemiologic methods. RESULTS: A comparison was made between two models; a stratified Cox model with age as the time-scale versus an un-stratified Cox model using the reference relative time-scale. The illustrative comparison used a UK cohort of cotton workers, with differing ages at entry to the study, with accrual over a time period and with long follow-up. Additionally, exponential and Weibull models were fitted since the reference relative time-scale analysis need not be restricted to the Cox model. A simulation study showed that analysis using the reference relative time-scale and analysis using chronological age had very similar power to detect a significant risk factor and both were equally unbiased. Further, the analysis using the reference relative time-scale supported fully-parametric survival modelling and allowed percentile predictions and mortality curves to be constructed. CONCLUSIONS: The reference relative time-scale was a viable alternative to chronological age, led to simplification of the modelling process and possessed the defined features of a good time-scale as defined in reliability theory. The reference relative time-scale has several interpretations and provides a unifying concept that links contemporary approaches in survival and reliability analysis to the traditional epidemiologic methods of Poisson regression and standardised mortality ratios. The community of practitioners has not previously made this connection.