Sample sizes of studies on diagnostic accuracy: literature survey

OBJECTIVES: To determine sample sizes in studies on diagnostic accuracy and the proportion of studies that report calculations of sample size. DESIGN: Literature survey. DATA SOURCES: All issues of eight leading journals published in 2002. METHODS: Sample sizes, number of subgroup analyses, and how often studies reported calculations of sample size were extracted. RESULTS: 43 of 8999 articles were non-screening studies on diagnostic accuracy. The median sample size was 118 (interquartile range 71-350) and the median prevalence of the target condition was 43% (27-61%). The median number of patients with the target condition--needed to calculate a test's sensitivity--was 49 (28-91). The median number of patients without the target condition--needed to determine a test's specificity--was 76 (27-209). Two of the 43 studies (5%) reported a priori calculations of sample size. Twenty articles (47%) reported results for patient subgroups. The number of subgroups ranged from two to 19 (median four). No studies reported that sample size was calculated on the basis of preplanned analyses of subgroups. CONCLUSION: Few studies on diagnostic accuracy report considerations of sample size. The number of participants in most studies on diagnostic accuracy is probably too small to analyse variability of measures of accuracy across patient subgroups.

Thermal adaptation and ecological speciation

Ecological speciation is defined as the emergence of reproductive isolation as a direct or indirect consequence of divergent ecological adaptation. Several empirical examples of ecological speciation have been reported in the literature which very often involve adaptation to biotic resources. In this review, we investigate whether adaptation to different thermal habitats could also promote speciation and try to assess the importance of such processes in nature. Our survey of the literature identified 16 animal and plant systems where divergent thermal adaptation may underlie (partial) reproductive isolation between populations or may allow the stable coexistence of sibling taxa. In many of the systems, the differentially adapted populations have a parapatric distribution along an environmental gradient. Isolation often involves extrinsic selection against locally maladapted parental or hybrid genotypes, and additional pre- or postzygotic barriers may be important. Together, the identified examples strongly suggest that divergent selection between thermal environments is often strong enough to maintain a bimodal genotype distribution upon secondary contact. What is less clear from the available data is whether it can also be strong enough to allow ecological speciation in the face of gene flow through reinforcement-like processes. It is possible that intrinsic features of thermal gradients or the genetic basis of thermal adaptation make such reinforcement-like processes unlikely but it is equally possible that pertinent systems are understudied. Overall, our literature survey highlights (once again) the dearth of studies that investigate similar incipient species along the continuum from initial divergence to full reproductive isolation and studies that investigate all possible reproductive barriers in a given system.

Blood vessel anomalities in the oral cavity of two calves

Two calves were presented with a congenital mass in the rostral mandibular gingiva. In both cases the masses relapsed after surgical removal. Histologically, the two masses were composed of irregularly arranged vascular cavities, embedded in loosely arranged stroma and alcian-blue PAS positive ground substance. Radiologically, a destruction of the alveolar cavity was recognized in both cases, which was in case 1 histologically compatible with bone resorption and remodeling associated with the infiltration of abundant granulation tissue. A literature survey revealed that no consistent criteria for a correct classification for vascular tumours exists, resulting in the fact that comparable lesions were named differently in the past. We therefore propose to classify such lesions as congential vascular malformation until distinct morphological, immunohistochemical and molecular genetic analysis criteria will exist.

Retinal vascular occlusion after vitrectomy with retrobulbar anesthesia-observational case series and survey of literature

BACKGROUND: Severe postoperative loss of vision has been occasionally reported as a rare complication of retrobulbar anesthesia, and several possible causes have been proposed in the literature. In this work, our own and other investigators' experiences with these complications are surveyed with a view to identifying its pathophysiology. PATIENTS: This observational case series refers to six patients who presented during a 3-month period with occlusion of either the central artery itself (n = 3) or a branch thereof (n = 3) 2-14 days after uneventful vitreoretinal surgery following retrobulbar anesthesia with a commercial preparation of mepivacaine (1% Scandicain®, Astra Chemicals, Sweden) containing methyl- and propyl parahydroxybenzoate as preservatives. RESULTS: Three of the patients carried risk factors, which were medically controlled. In three individuals, vasoocclusion was observed after a second vitreoretinal intervention, which was performed 3-12 months after uneventful primary surgery. Good visual recovery was observed in only one instance. CONCLUSIONS: In patients who were anesthetized with preservative-free mepivacaine, no vasoocclusion occurred. In individuals who were anesthetized with mepivacaine containing the preservatives methyl- and propyl parahydroxybenzoate, a tenfold increase in the incidence of eyes requiring re-operation was documented, with a 2- to 14-day lapse in the onset of vasoocclusion. These findings reveal a possible implication of preservatives contained in the local anesthetic solution for the vasoocclusive events. Due to this potential hazard, the use of preservative-free preparations of local anesthesia in ocular surgery is emphasized in order to prevent this sight-threatening complication.

Rarely selected distractors in high stakes medical multiple-choice examinations and their recognition by item authors: A simulation and survey

Background Many medical exams use 5 options for multiple choice questions (MCQs), although the literature suggests that 3 options are optimal. Previous studies on this topic have often been based on non-medical examinations, so we sought to analyse rarely selected, 'non-functional' distractors (NF-D) in high stakes medical examinations, and their detection by item authors as well as psychometric changes resulting from a reduction in the number of options. Methods Based on Swiss Federal MCQ examinations from 2005-2007, the frequency of NF-D (selected by <1% or <5% of the candidates) was calculated. Distractors that were chosen the least or second least were identified and candidates who chose them were allocated to the remaining options using two extreme assumptions about their hypothetical behaviour: In case rarely selected distractors were eliminated, candidates could randomly choose another option - or purposively choose the correct answer, from which they had originally been distracted. In a second step, 37 experts were asked to mark the least plausible options. The consequences of a reduction from 4 to 3 or 2 distractors - based on item statistics or on the experts' ratings - with respect to difficulty, discrimination and reliability were modelled. Results About 70% of the 5-option-items had at least 1 NF-D selected by <1% of the candidates (97% for NF-Ds selected by <5%). Only a reduction to 2 distractors and assuming that candidates would switch to the correct answer in the absence of a 'non-functional' distractor led to relevant differences in reliability and difficulty (and to a lesser degree discrimination). The experts' ratings resulted in slightly greater changes compared to the statistical approach. Conclusions Based on item statistics and/or an expert panel's recommendation, the choice of a varying number of 3-4 (or partly 2) plausible distractors could be performed without marked deteriorations in psychometric characteristics.

Survey on controversies in airway management among anesthesiologists in the UK, Austria and Switzerland

While surveys about anesthesia practice appear regularly in the anesthesia literature, they are usually bound to one country. We compared the approach to specific airway management issues among anesthesiologists from three different European countries.

Endoscopy for repeatedly ingested sharp foreign bodies in patients with borderline personality disorder: an international survey

The general guidelines on the management of ingested foreign bodies (FBs) do not address specific aspects raised by psychiatric patients, particularly in patients with borderline personality disorders (BPD) who repeatedly ingest FBs. The aim of this survey was to collect data on experience and opinions on the management of FBs in psychiatric patients with BPD and to review the relevant literature.

Towards a taxonomy of common factors in psychotherapy-results of an expert survey

BACKGROUND: How change comes about is hotly debated in psychotherapy research. One camp considers 'non-specific' or 'common factors', shared by different therapy approaches, as essential, whereas researchers of the other camp consider specific techniques as the essential ingredients of change. This controversy, however, suffers from unclear terminology and logical inconsistencies. The Taxonomy Project therefore aims at contributing to the definition and conceptualization of common factors of psychotherapy by analyzing their differential associations to standard techniques. METHODS: A review identified 22 common factors discussed in psychotherapy research literature. We conducted a survey, in which 68 psychotherapy experts assessed how common factors are implemented by specific techniques. Using hierarchical linear models, we predicted each common factor by techniques and by experts' age, gender and allegiance to a therapy orientation. RESULTS: Common factors differed largely in their relevance for technique implementation. Patient engagement, Affective experiencing and Therapeutic alliance were judged most relevant. Common factors also differed with respect to how well they could be explained by the set of techniques. We present detailed profiles of all common factors by the (positively or negatively) associated techniques. There were indications of a biased taxonomy not covering the embodiment of psychotherapy (expressed by body-centred techniques such as progressive muscle relaxation, biofeedback training and hypnosis). Likewise, common factors did not adequately represent effective psychodynamic and systemic techniques. CONCLUSION: This taxonomic endeavour is a step towards a clarification of important core constructs of psychotherapy. KEY PRACTITIONER MESSAGE: This article relates standard techniques of psychotherapy (well known to practising therapists) to the change factors/change mechanisms discussed in psychotherapy theory. It gives a short review of the current debate on the mechanisms by which psychotherapy works. We provide detailed profiles of change mechanisms and how they may be generated by practice techniques.

The significant effect of endometriosis on physical, mental and social wellbeing: results from an international cross-sectional survey.

STUDY QUESTION To what extent do the management of endometriosis and the symptoms that remain after treatment affect the quality of life in women with the disease? SUMMARY ANSWER Many women with endometriosis had impaired quality of life and continued to suffer from endometriosis-associated symptoms even though their endometriosis has been managed in tertiary care centres. WHAT IS KNOWN ALREADY The existing literature indicates that quality of life and work productivity is reduced in women with endometriosis. However, most studies have small sample sizes, are treatment related or examine newly diagnosed patients only. STUDY DESIGN, SIZE, DURATION A cross-sectional questionnaire-based survey among 931 women with endometriosis treated in 12 tertiary care centres in 10 countries. PARTICIPANTS/MATERIALS, SETTING, METHODS Women diagnosed with endometriosis who had at least one contact related to endometriosis-associated symptoms during 2008 with a participating centre were enrolled into the study. The study investigated the effect of endometriosis on education, work and social wellbeing, endometriosis-associated symptoms and health-related quality of life, by using questions obtained from the World Endometriosis Research Foundation (WERF) GSWH instrument (designed and validated for the WERF Global Study on Women's Health) and the Short Form 36 version 2 (SF-36v2). MAIN RESULTS AND THE ROLE OF CHANCE Of 3216 women invited to participate in the study, 1450 (45%) provided informed consent and out of these, 931 (931/3216 = 29%) returned the questionnaires. Endometriosis had affected work in 51% of the women and affected relationships in 50% of the women at some time during their life. Dysmenorrhoea was reported by 59%, dyspareunia by 56% and chronic pelvic pain by 60% of women. Quality of life was decreased in all eight dimensions of the SF-36v2 compared with norm-based scores from a general US population (all P < 0.01). Multivariate regression analysis showed that number of co-morbidities, chronic pain and dyspareunia had an independent negative effect on both the physical and mental component of the SF-36v2. LIMITATIONS, REASONS FOR CAUTION The fact that women were enrolled in tertiary care centres could lead to a possible over-representation of women with moderate-to-severe endometriosis, because the participating centres typically treat more complex and referred cases of endometriosis. The response rate was relatively low. Since there was no Institute Review Board approval to do a non-responder investigation on basic characteristics, some uncertainty remains regarding the representativeness of the investigated population. WIDER IMPLICATIONS OF THE FINDINGS This international multicentre survey represents a large group of women with endometriosis, in all phases of the disease, which increases the generalizability of the data. Women still suffer from frequent symptoms, despite tertiary care management, in particular chronic pain and dyspareunia. As a result their quality of life is significantly decreased. A patient-centred approach with extensive collaboration across disciplines, such as pain specialists, psychologists, sexologists and social workers, may be a valuable strategy to improve the long-term care of women with endometriosis. STUDY FUNDING/COMPETING INTEREST(S) The WERF EndoCost study is funded by the World Endometriosis Research Foundation (WERF) through grants received from Bayer Schering Pharma AG, Takeda Italia Farmaceutici SpA, Pfizer Ltd and the European Society of Human Reproduction and Embryology. The sponsors did not have a role in the design and conduct of the study; collection, management, analysis and interpretation of the data; and preparation, review or approval of the manuscript. L.H. is the chief executive and T.D. was a board member of WERF at the time of funding. T.D. holds the Merck-Serono Chair in Reproductive Medicine and Surgery, and the Ferring Chair in Reproductive Medicine at the Katholieke Universiteit Leuven in Belgium and has served as consultant/research collaborator for Merck-Serono, Schering-Plough, Astellas and Arresto.

Ethnolinguistic survey of westernmost Arunachal Pradesh: A field worker's impressions

The area between Bhutan in the west, Tibet in the north, the Kameng river in the east and Assam in the south is home to at least six distinct phyla of the Trans-Himalayan (Tibeto-Burman, Sino-Tibetan) language family. These phyla encompass a minimum of 11, but probably 15 or even more mutually unintelligible languages, all showing considerable internal dialect variation. Previous literature provided largely incomplete or incorrect accounts of these phyla. Based on recent field research, this article discusses in detail the several languages of four phyla whose speakers are included in the Monpa Scheduled Tribe, providing the most accurate speaker data, geographical distribution, internal variation and degree of endangerment. The article also provides some insights into the historical background of the area and the impact this has had on the distribution of the ethnolinguistic groups.

A survey on the feeding of eventing horses during competition

This study aims at the comparison of the actual feeding of horses with the recommendations from the literature, and it studies the effects of feeding and exercise on several blood metabolic parameters before and after exercise. Blood samples were collected from 25 horses during one-star eventing competitions and evaluated for blood glucose, insulin, lactate, free fatty acids and triglyceride levels. Questionnaires on the feeding practices of the horses were evaluated. The questionnaires revealed that during training, and on tournament days, horses received on average 4.3 kg of concentrate per day (min. 1.54 kg, max. 8 kg). The statistical analysis showed no significant effect of the amount of concentrate fed before exercise on the measured blood values. Oil was supplied as a supplementary energy source to 30% of the horses, but most of them only received very small quantities (0.02–0.4 l/day). Five horses (20%) had no access to salt supplements at all, and eleven horses (45%) had no access to salt on tournament days. Fifteen horses (60%) were supplied with mineral feed. Twenty-one horses (84%) had daily access to pasture during the training period. During competition, 55% of the horses received roughage ad libitum, compared with 37% during training. The majority of the horses received less roughage on days before the cross-country competition. It could not be ascertained whether feeding a large amounts of roughage had a beneficial effect on performance, because only a few horses in this study were fed with very restrictive roughage. Feeding of most of the horses was in agreement with the recommendations from the literature, except the need for sodium and chloride. The sodium and chloride need for sport horses may be overestimated in literature and needs to be re-evaluated.

Cutaneous Collagenous Vasculopathy: A Rare Form of Microangiopathy Successfully Treated with a Combination of Multiplex Laser and Optimized Pulsed Light with a Review of the Literature.

Cutaneous collagenous vasculopathy (CCV) is a rare idiopathic microangiopathy of the cutaneous vasculature characterized histologically by the presence of dilated small blood vessels with flat endothelial cells and thickened walls containing hyaline material in the upper dermis. We report an elderly patient presenting with an extensive form of CCV involving the trunk, upper and lower limbs. She was treated with Multiplex PDL 595-nm/Nd:YAG 1,064-nm laser and optimized pulsed light. This approach, which has never been reported for CCV so far, resulted in a striking and almost complete clearance of the widespread lesions. We here review our knowledge about CCV and therapeutic options available with a survey of the literature.

Breastfeeding-Associated Hypernatremia: A Systematic Review of the Literature.

There are increasing reports on hypernatremia, a potentially devastating condition, in exclusively breastfed newborn infants. Our purposes were to describe the clinical features of the condition and identify the risk factors for it. We performed a review of the existing literature in the National Library of Medicine database and in the search engine Google Scholar. A total of 115 reports were included in the final analysis. Breastfeeding-associated neonatal hypernatremia was recognized in infants who were ≤ 21 days of age and had ≥ 10% weight loss of birth weight. Cesarean delivery, primiparity, breast anomalies or breastfeeding problems, excessive prepregnancy maternal weight, delayed first breastfeeding, lack of previous breastfeeding experience, and low maternal education level were significantly associated with breastfeeding-associated hypernatremia. In addition to excessive weight loss (≥ 10%), the following clinical findings were observed: poor feeding, poor hydration state, jaundice, excessive body temperature, irritability or lethargy, decreased urine output, and epileptic seizures. In conclusion, the present survey of the literature identifies the following risk factors for breastfeeding-associated neonatal hypernatremia: cesarean delivery, primiparity, breastfeeding problems, excessive maternal body weight, delayed breastfeeding, lack of previous breastfeeding experience, and low maternal education level.