Inter-observer comparisons of ophthalmoscopic assessment of diabetic retinopathy

Abstract
Five hundred patients attending a general diabetic clinic were examined ophthalmoscopically both by a non-ophthalmic practitioner (NOP) and by an ophthalmologist. The findings were recorded on separate data sheets and the staging of diabetic retinopathy (DR) and grading of diabetic maculopathy by the NOP is compared with that of the ophthalmologist.
Comparisons are made for NOPs collectively and for subgroups of NOPs of different levels of experience in ophthalmoscopic assessment of DR. A profile is presented of DR occurring in this diabetic clinic population. The comparison studies show significant variations in ability of different observer groups and also between observers of the same status. It is concluded that an ophthalmologist is a necessary member of a diabetic care team.     

On Theil's errors

Summary We take a fresh look at Theil's BLUS residuals and ask why they have gone out of fashion. All our simulation experiments indicate that tests based on BLUS residuals have higher power than those based on the more popular recursive residuals, even in those cases (structural breaks) where intuition would favour the recursive residuals.     

Protein structural homology: a metric approach

The flexibility of the polypeptide fold of proteins is essentially due to the rotational freedom about the main chain bonds involving C_α atoms. The polypeptide fold can therefore be represented by virtual bonds joining consecutive C_α atoms. The ordered sequence of virtual torsion and bond angles involving these bonds can be used to specify the fold. Such representations can then be compared to reveal structural similarities using the Needleman & Wünsch algorithm, which has been developed for comparison of amino acid sequences. Such an approach is presented and illustrated with examples. The method is suitable for detecting structural similarities that extend over 7 or more residues.     

A two-period crossover design for the comparison of two active treatments and placebo

This paper discusses a two-period crossover design for the comparison of two active treatments (A and B) and placebo (P) for relief of recurrent symptoms of a chronic health disorder. It is based on blocks of ten patients for which the treatment sequences A:B and B:A are each assigned to three patients and the sequences A:P, P:A, B:P, and P:B are each assigned to one patient; thus, treatment periods have a 2:2:1 allocation for A, B, and P. The principal model for analysis of this design involves additive subject effects, period effects, and treatment effects. Analysis of within-patient differences provides an estimate of the comparison between active treatments with variance (2vw/7r) and an estimate of the comparison between an active treatment and placebo with variance (4vw/7r); here vw is the within-patient variance and r is the number of blocks of ten patients. Analyses which address carryover effects and treatment effects adjusted for carryover effects are also described. An example using simulated data on relief of recurrent gastrointestinal pain illustrates the methodology.     

Deaths in winter: Can Britain learn from Europe?

There is a substantial increase in the number of deaths in winter in the United Kingdom. This is also seen in some, but not all, European countries. Almost 60% of the the variation among countries can be explained by the minimum average monthly temperature and the gross national product per capita. Seasonal variation is lowest in those countries with cold winters, suggesting that insulation may be important. It is also low in the more wealthy countries. The implications for health service policy of these finding are discussed.Some of the residual variation may be explained by known factors, such as low cost geo-thermal energy in Iceland, but much remains unexplained. There is a need for more research in this field.     

Are performance indicators generic? The international experience of the Quality Indicator Project

Performance indicators for healthcare organizations represent a strategy for accountability worldwide. A universal approach to either the design for indicators or their applicability to local needs remains a work in progress. The Maryland Hospital Association's Quality Indicator Project (QIP) is the only indicator-based performance measurement system used worldwide. This paper presents, for the first time in QIP's 17 years of existence, data showing why MHA's QIP may qualify as the most accepted generic methodology for healthcare performance measurement and evaluation.     

A SAS macro for testing differences among three or more independent groups using Kruskal-Wallis and Nemenyi tests

As a nonparametric method,the Kruskal-Wallis test is widely used to compare three or more independent groups when an ordinal or interval level of data is available,especially when the assump-tions of analysis of variance (ANOVA) are not met.If the Kruskal-Wallis statistic is statistically signifi-cant,Nemenyi test is an alternative method for further pairwise multiple comparisons to locate the source of significance.Unfortunately,most popular statistical packages do not integrate the Nemenyi test,which is not easy to be calculated by hand.We described the theory and applications of the Kruskal-Wallis and Nemenyi tests,and presented a flexible SAS macro to implement the two tests.The SAS macro was demonstrated by two examples from our cohort study in occupational epidemiology.It provides a useful tool for SAS users to test the differences among three or more independent groups using a nonparametric method.     

“Still the same and better off than others?”: social and temporal comparisons in old age

Cognitive adaptation in the elderly and the motivated use of temporal and social comparisons set the conceptual frame for the present study. Three research questions were investigated in a sample of 2.129 persons aged between 50 and 90 years. First, the direction of social and temporal comparisons for three domains (physical fitness, mental fitness, psychological resilience) was studied, and findings did show that especially lateral followed by upward comparisons were most frequent under both perspectives; downward comparisons clearly showed the least frequency. Second, the distribution of comparison directions was investigated across four age groups. These analyses showed that upward comparisons increased and lateral comparisons decreased across age groups; differential results were observed for the domains under consideration. Third, the relation between social and temporal comparisons and self-esteem was studied. Results obtained here indicated a motivated use of specific comparison directions since downward social comparisons and upward temporal comparisons were most frequent in persons with low self-esteem. Taken together, the study underlines the different functions of social and temporal comparisons in adulthood and old age; it indicates a predominant need for consensus and consistency, and it highlights the importance of self-esteem in cognitive adaptation.