Whether the aim is to diagnose individuals or estimate prevalence, many epidemiological studies have demonstrated the successful use of tests on pooled sera. These tests detect whether at least one sample in the pool is positive. Although originally designed to reduce diagnostic costs, testing pools also lowers false positive and negative rates in low prevalence settings and yields more precise prevalence estimates. Current methods are aimed at estimating the average population risk from diagnostic tests on pools. In this article, we extend the original class of risk estimators to adjust for covariates recorded on individual pool members. Maximum likelihood theory provides a flexible estimation method that handles different covariate values in the pool, different pool sizes, and errors in test results. In special cases, software for generalized linear models can be used. Pool design has a strong impact on precision and cost efficiency, with covariate-homogeneous pools carrying the largest amount of information. We perform joint pool and sample size calculations using information from individual contributors to the pool and show that a good design can severely reduce cost and yet increase precision. The methods are illustrated using data from a Kenyan surveillance study of HIV. Compared to individual testing, age-homogeneous, optimal-sized pools of average size seven reduce cost to 44% of the original price with virtually no loss in precision.

• DCE-MRI plays an important role in differentiating benign from malignant cartilage tumours. • Retrospective study defined a threshold for 100 % detection of chondrosarcoma with DCE-MRI. • The threshold values were relative enhancement = 2 and slope = 4.5. • One hundred per cent chondrosarcoma detection corresponds with 36.7 % false-positive diagnosis of enchondroma. • Standard MRI is complementary to DCE-MRI in differentiating cartilaginous tumours.

Hypothesis: The purpose of this study was to investigate the three dimensional orientation of the glenoid plane and the scapular plane. Different definitions of the glenoid plane were used and different planes were measured and we hypothesed that the 3-D plane with the least variation would be best to define the most reliable glenoid plane. Methods: We studied 150 CT scans from non-pathological shoulders from patients between 18 and 80. The scapular plane and five different glenoid planes were determined: an inferior, anterior, posterior, superior and neutral glenoid plane. Of all planes version and inclination angles were measured. Because all examinations were done in a standardized position to the coronal, sagittal and transverse plane of the body the scapular plane could be defined versus the coronal, sagittal and transverse planes of the body. Results: The version (mean: 3.76) of the inferior glenoid plane showed a significantly lower standard deviation than the version of the anterior (p<0.001), posterior (p=0.001) and superior (p=0.001) glenoid plane (ANOVA). For inclination all planes have a similar variance. The scapular plane was different between gender ( P=0.022) and correlated with age. Conclusion: This study showed that the retroversion of the inferior glenoid is reasonably constant. The osseous anthropometry of the inferior glenoid can offer a reproducible point of reference to be used in prosthetic surgery of the shoulder. Revision of the MS. Ref. No.: JSES-D-09-00274Comments from the Editors and Reviewers: Associate Editor's comment: Unfortunately the reviewer are not convinced that this study adds much useful new data to literature. Weak points are: Indication for CT scan examination of the contralateral shoulder not given: The patients that were included had a CT scan examination of the contralateral (pathologic) shoulder for instability (30), AC-joint arthritis (33), Rotator Cuff tears (33), (partial (5), Full thickness (28)), calcifying tendinitis (12), frozen shoulder (8), subacromial impingement (17), tendinitis of the long head of biceps brachii (12), fractures of the proximal humerus (5). Those pathologies are included in the manuscript.A special selection (Instability, osteoarthritis, cuff tear arthropathy) might have influenced the results. This is a study about the normal shoulder and we hope to do in the future studies on the pathological shoulder as one might expect this might differ from the normal shoulder. The clinical examination of the shoulder as well as the history was negative of the included shoulder and this is mentioned in the manuscript.Ethical considerations: Was the consensus of the patients for the scan of the contralateral shoulder and the ethical committee given (difference of exposure both versus one shoulder?). Ethical approval was cleared from the ethics committee (EC/2009-099/Svdm). The patients received no extra irradiation because it is difficult to impossible to positioning one shoulder more central in the CT-scan to narrow the window of exposure an...

SummarySeroprevalence studies are crucial in HIV control programs but too expensive at district level. We evaluated the applicability of pooling sera and how it can reduce cost and affect accuracy at district level. 740 samples collected from antenatal clinic attendants for a sentinel survey in a rural Kenyan district were screened individually and in pools of 10. The seroprevalence when measured individually was 7.30%, while the calculated seroprevalence from pooled testing was 7.49%. Pooling was practicable and reduced costs by 62% for a marginal loss of accuracy. It is a useful tool in increasing the affordability of surveillance at district level. A pool size of 8 would have resulted in optimal cost reduction at minimal loss of accuracy.

SummaryFive cases of blackwater fever (BWF) are described, all of whom had a history of recent quinine therapy. In two cases a second haemolytic crisis was induced by halofantrine, in one case also a third. Increasing frequency of this syndrome with its dramatic clinical presentation is to be expected as imported P. falciparum infection, parasite resistance to chloroquine and the use of quinine and other related antimalarials become more frequent.