Assessing the relationship between markers of glycemic control through flexible copula regression models.

Glycated haemoglobin (HbA1c) is a sensitive marker of blood glucose in patients with diabetes. However, levels can vary considerably, even amongst individuals with similar mean blood glucose concentrations. Other glycated proteins, such as fructosamine, can also act as blood sugar markers, but estimating HbA1c and fructosamine via independent models may lead to errors of interpretation regarding disease severity. From a clinical standpoint, it would be of great interest to know the factors that affect the mean concentration of both HbA1c and fructosamine, which influence the variability in the concentrations of these glycated markers and cause HbA1c/fructosamine discordance. Flexible models are required to illustrate the behaviour of these variables as well as the association between them. This work reviews existing models that might serve in this regard. Flexible copula regression models using splines were used to provide a better understanding of the behaviour of both glycated proteins and the relationship between them under the possible influence of different covariates. This work shows the usefulness of this type of models in practise and provides a basis for their clinical interpretation by means of an understandable case study. Ultimately, to better understand the effects of each continuous covariate, they are represented at the true scale of the response variables.

Epidemiology of suicide in Spain, 1981-2008: a spatiotemporal analysis.

OBJECTIVE: To analyse the epidemiology of suicide, and compare its occurrence between the sexes and in various regions in Spain. METHOD: Age-specific analysis and spatiotemporal analysis to analyse death by suicide between 1981 and 2008 in Spain. STUDY DESIGN: Ecological study. RESULTS: Death by suicide has decreased since the 1990s in Spain, although peaks in suicides correspond with times of economic crisis. Death by suicide was more common among men than among women, although the suicide mortality rate increased over the study period among women aged 35-49 years. Geographical analysis showed that rural populations and areas with historically higher levels of unemployment have higher suicide rates. In contrast, less-populated regions have lower suicide rates. CONCLUSION: Suicides in Spain exhibit a clear geographic pattern and occur at different rates between the genders. The results suggest an increasing number of suicides among women aged 35-49 years over the study period.

Validation of the German revised Addenbrooke's cognitive examination for detecting mild cognitive impairment, mild dementia in alzheimer's disease and frontotemporal lobar degeneration.

BACKGROUND/AIMS: The diagnostic accuracy of the German version of the revised Addenbrooke's Cognitive Examination (ACE-R) in identifying mild cognitive impairment (MCI), mild dementia in Alzheimer's disease (AD) and mild dementia in frontotemporal lobar degeneration (FTLD) in comparison with the conventional Mini Mental State Examination (MMSE) was assessed. METHODS: The study encompasses 76 cognitively healthy elderly individuals, 75 patients with MCI, 56 with AD and 22 with FTLD. ACE-R and MMSE were validated against an expert diagnosis based on a comprehensive diagnostic procedure. Statistical analysis was performed using the receiver operating characteristic method and regression analyses. RESULTS: The optimal cut-off score for the ACE-R for detecting MCI, AD, and FTLD was 86/87, 82/83 and 83/84, respectively. ACE-R was superior to MMSE only in the detection of patients with FTLD [area under the curve (AUC): 0.97 vs. 0.92], whilst the accuracy of the two instruments did not differ in identifying MCI and AD. The ratio of the scores of the memory ACE-R subtest to verbal fluency subtest contributed significantly to the discrimination between AD and FTLD (optimal cut-off score: 2.30/2.31, AUC: 0.77), whereas the MMSE and ACE-R total scores did not. CONCLUSION: The German ACE-R is superior to the most commonly employed MMSE in detecting mild dementia in FTLD and in the differential diagnosis between AD and FTLD. Thus it might serve as a valuable instrument as part of a comprehensive diagnostic workup in specialist centres/clinics contributing to the diagnosis and differential diagnosis of the cause of dementia.

Preservation of putative continence nerves during radical retropubic prostatectomy leads to more rapid return of urinary continence.

OBJECTIVES: Urinary incontinence is a significant complication of radical pelvic surgery. A better understanding of the neuroanatomy of the rhabdosphincter has led to the modification of the radical retropubic prostatectomy to optimize the recovery of postoperative urinary control. METHODS: Mock radical retropubic prostatectomy was performed on fresh cadavers to determine which surgical maneuvers could injure what may be the continence nerves. To assess the clinical significance of modifying the radical retropubic prostatectomy based on these anatomic studies, a contemporary series of 60 consecutive patients who underwent radical retropubic prostatectomy with continence nerve preservation was compared with a control group of 38 consecutive patients who had a standard anatomic radical retropubic prostatectomy. RESULTS: At the level of the prostatic apex, both the pelvic and pudendal nerves gave intrapelvic branches that bilaterally coursed to the external urinary sphincter to enter at the 5 and 7 o'clock positions. The mock radical prostatectomy revealed that the nerves to the external urinary sphincter were most prone to injury when a right angle clamp was used to develop a plane between the posterior rhabdosphincter and anterior rectum and if the urethral anastomotic sutures were placed at the 5 and 7 o'clock positions. In addition, blunt dissection of the tips of the seminal vesicles injured the inferior hypogastric plexus. Modifications to preserve the continence nerves were incorporated in the anatomic radical prostatectomy. Although overall continence rates were similar for the two groups (98.3% for continence nerve-preserving radical prostatectomy versus 92. 1% for standard prostatectomy), continence nerve preservation decreased the time to achieve continence. CONCLUSIONS: During radical retropubic prostatectomy, surgical maneuvers that avoid injury to the continence nerves resulted in the more rapid return of urinary control.

Discussion of "the evolution of boosting algorithms" and "extending statistical boosting".

This article is part of a For-Discussion-Section of Methods of Information in Medicine about the papers "The Evolution of Boosting Algorithms - From Machine Learning to Statistical Modelling" and "Extending Statistical Boosting - An Overview of Recent Methodological Developments", written by Andreas Mayr and co-authors. It is introduced by an editorial. This article contains the combined commentaries invited to independently comment on the Mayr et al. papers. In subsequent issues the discussion can continue through letters to the editor.

Short-term influence of elevation of plasma homocysteine levels on cognitive function in young healthy adults.

BACKGROUND: Acute homocysteine elevation has been shown to have a significant impact on cognitive function in animal models. OBJECTIVES: Investigation of the short-term impact of elevation of plasma homocysteine levels through a dietary intervention on cognitive abilities of young healthy adults. PARTICIPANTS: 100 healthy medical students of both genders were enrolled in the study. DESIGN AND MEASUREMENTS: Homocysteine levels and cognitive abilities were measured at 08:30 (before breakfast) and at 15:00 (two hours after lunch and six hours after breakfast). Food intake was restricted to specified comestibles. The cognitive assessment comprised a version of the Short Test for General Intelligence, three subtests of the Syndrome Short Test and the Stroop test. RESULTS: At 15:00 plasma homocysteine was significantly elevated in 56 participants (P < 0.00001), whilst in 44 it was decreased (P < 0.00001) in comparison to baseline (08:30). The decrease was however of limited clinical significance. The differences in the changes in cognitive performance between the two groups did not attain statistical significance (P > 0.05) and the direction of the changes did not differ between them. Accordingly, the multiple linear regression analysis did not reveal an important influence of homocysteine elevation on cognitive performance variations. CONCLUSIONS: Significant increase of plasma homocysteine is not associated with a straightforward inhibitory or facilitatory short-term effect on physiological cognitive parameters in young healthy adults.