Estimating the sample mean and standard deviation from commonly reported quantiles in meta-analysis

Researchers increasingly use meta-analysis to synthesize the results of several studies in order to estimate a common effect. When the outcome variable is continuous, standard meta-analytic approaches assume that the primary studies report the sample mean and standard deviation of the outcome. However, when the outcome is skewed, authors sometimes summarize the data by reporting the sample median and one or both of (i) the minimum and maximum values and (ii) the first and third quartiles, but do not report the mean or standard deviation. To include these studies in meta-analysis, several methods have been developed to estimate the sample mean and standard deviation from the reported summary data. A major limitation of these widely used methods is that they assume that the outcome distribution is normal, which is unlikely to be tenable for studies reporting medians. We propose two novel approaches to estimate the sample mean and standard deviation when data are suspected to be non-normal. Our simulation results and empirical assessments show that the proposed methods often perform better than the existing methods when applied to non-normal data

Economic evaluation of screening for open angle glaucoma

Objectives: The aim of this study was to assess the cost-effectiveness of screening for open-angle glaucoma (OAG) in the United Kingdom, given that OAG is an important cause of blindness worldwide. Methods: A Markov model was developed to estimate lifetime costs and benefits of a cohort of patients facing, alternatively, screening or current opportunistic case finding strategies. Strategies, varying in how screening would be organized (e.g., invitation for assessment by a glaucoma-trained optometrist [GO] or for simple test assessment by a technician) were developed, and allowed for the progression of OAG and treatment effects. Data inputs were obtained from systematic reviews. Deterministic and probabilistic sensitivity analyses were performed. Results: Screening was more likely to be cost-effective as prevalence increased, for 40 year olds compared with 60 or 75 year olds, when the re-screening interval was greater (10 years), and for the technician strategy compared with the GO strategy. For each age cohort and at prevalence levels of ≤1 percent, the likelihood that either screening strategy would be more cost-effective than current practice was small. For those 40 years of age, “technician screening” compared with current practice has an incremental cost-effectiveness ratio (ICER) that society might be willing to pay when prevalence is 6 percent to 10 percent and at over 10 percent for 60 year olds. In the United Kingdom, the age specific prevalence of OAG is much lower. Screening by GO, at any age or prevalence level, was not associated with an ICER < £30,000. Conclusions: Population screening for OAG is unlikely to be cost-effective but could be for specific subgroups at higher risk.This study was developed from a health technology assessment on the clinical and cost-effectiveness of screening for open-angle glaucoma (OAG), funded by the National Institute for Health Research Health Technology Assessment Programme (project no. 04/08/02).Peer reviewedAuthor versio

A clinical assessment tool for midwives undertaking the Newborn Infant Physical Examination

The role of midwives has evolved over the last two decades, and in the United Kingdom midwives and advanced neonatal nurse practitioners undertake roles that traditionally were undertaken by junior doctors. The Newborn Infant Physical Examination (NIPE) is performed within the first 72 hours of birth (Lanlehin, 2011), and enables midwives to provide a holistic assessment of neonates and their mothers, as well as confirming normality, identifying abnormalities, and providing early intervention for at risk neonates. The aim of this paper is to discuss the usefulness of the Newborn and Infant Assessment Tool (NIAT) which was originally used as an oral assessment tool for a health professional undertaking the NIPE course. However, it became clear over the course of 10 years that not only is this a framework for assessing students' application of theoretical knowledge to practice scenarios, it is also an assessment tool that can be used by trained midwives, medical staff, and student nurses to enhance clinical decision-making when faced with an unwell baby

Tyrol Prostate Cancer Demonstration Project : early detection, treatment, outcome, incidence and mortality

This study aimed to evaluate the effectiveness of a well-controlled programme of early detection and treatment of prostate cancer in the population of Tyrol, Austria, where such a programme of early detection and treatment was initiated in 1988 and where prostate-specific antigen (PSA) testing was offered for free to all men aged 45-75 years from 1993. Comparison of prostate cancer mortality rates in Tyrol and the rest of Austria was accomplished through a generalized additive model. A piecewise linear change-point Poisson regression model was used to compare mortality rates in Tyrol and the rest of Austria. Standardized mortality ratios were calculated with reference to the mortality rates in 1986-1990. In all, 86.6% of eligible men have been tested at least once since 1993. Cancer deaths in Tyrol in 2005 were 54% (95% confidence interval [CI] 34-69%) lower than expected compared with 29% (95% CI 22-35%) in the rest of Austria. The decreasing trend in prostate cancer mortality was significantly greater in Tyrol compared with the rest of Austria (P = 0.001). A significant migration to lower stage disease occurred and radical prostatectomy was associated with low morbidity. In the Tyrol region where treatment is freely available to all patients, where widespread PSA testing and treatment with curative intent occurs, there was a reduction in prostate cancer mortality rates which was significantly greater than the reduction in the rest of Austria. This reduction in prostate cancer mortality is most probably due to early detection, consequent down-staging and effective treatment of prostate cancer

Bowel cancer screening in England: a qualitative study of GPs' attitudes and information needs

BACKGROUND: The National Health Service Bowel Cancer Screening Programme is to be introduced in England during 2006. General Practitioners are a potentially important point of contact for participants throughout the screening process. The aims of the study were to examine GPs' attitudes and information needs with regard to bowel cancer screening, with a view to developing an information pack for primary care teams that will be circulated prior to the introduction of the programme. METHODS: 32 GPs participated in semi-structured telephone interviews. 18 of these had participated in the English Bowel Screening Pilot, and 14 had not. Interviews covered attitudes towards the introduction of the Bowel Cancer Screening Programme, expected or actual increases in workload, confidence in promoting informed choice, and preferences for receiving information about the programme. RESULTS: GPs in the study were generally positive about the introduction of the Bowel Cancer Screening Programme. A number of concerns were identified by GPs who had not taken part in the pilot programme, particularly relating to patient welfare, patient participation, and increased workload. GPs who had taken part in the pilot reported holding similar concerns prior to their involvement. However, in many cases these concerns were not confirmed through GPs experiences with the pilot. A number of specific information needs were identified by GPs to enable them to provide a supportive role to participants in the programme. CONCLUSION: The study has found considerable GP support for the introduction of the new Bowel Cancer Screening Programme. Nonetheless, GPs hold some significant reservations regarding the programme. It is important that the information needs of GPs and other members of the primary care team are addressed prior to the roll-out of the programme so they are equipped to promote informed choice and provide support to patients who consult them with queries regarding screening

Overdiagnosis and overtreatment of breast cancer: Overdiagnosis in randomised controlled trials of breast cancer screening

Data from randomised controlled trials of mammographic screening can be used to determine the extent of any overdiagnosis, as soon as either a time equivalent to the lead-time has elapsed after the final screen, or the control arm has been offered screening. This paper reviews those randomised trials for which breast cancer incidence data are available. In recent trials in which the control group has not been offered screening, an excess incidence of breast cancer remains after many years of follow-up. In those trials in which the control arm has been offered screening, although there is a possible shift from invasive to in situ disease, there is no evidence of overdiagnosis as a result of incident screens

Outcomes of the Bowel Cancer Screening Programme (BCSP) in England after the first 1 million tests

The Bowel Cancer Screening Programme in England began operating in 2006 with the aim of full roll out across England by December 2009. Subjects aged 60-69 are being invited to complete three guaiac faecal occult blood tests (6 windows) every 2 years. The programme aims to reduce mortality from colorectal cancer by 16% in those invited for screening

Screening for breast cancer : medicalization, visualization and the embodied experience

Women’s perspectives on breast screening (mammography and breast awareness) were explored in interviews with midlife women sampled for diversity of background and health experience. Attending mammography screening was considered a social obligation despite women’s fears and experiences of discomfort. Women gave considerable legitimacy to mammography visualizations of the breast, and the expert interpretation of these. In comparison, women lacked confidence in breast awareness practices, directly comparing their sensory capabilities with those of the mammogram, although mammography screening did not substitute breast awareness in a straightforward way. The authors argue that reliance on visualizing technology may create a fragmented sense of the body, separating the at risk breast from embodied experience

Changes in and predictors of length of stay in hospital after surgery for breast cancer between 1997/98 and 2004/05 in two regions of England: a population-based

BACKGROUND Decreases in length of stay (LOS) in hospital after breast cancer surgery can be partly attributed to the change to less radical surgery, but many other factors are operating at the patient, surgeon and hospital levels. This study aimed to describe the changes in and predictors of length of stay (LOS) in hospital after surgery for breast cancer between 1997/98 and 2004/05 in two regions of England. METHODS Cases of female invasive breast cancer diagnosed in two English cancer registry regions were linked to Hospital Episode Statistics data for the period 1st April 1997 to 31st March 2005. A subset of records where women underwent mastectomy or breast conserving surgery (BCS) was extracted (n = 44,877). Variations in LOS over the study period were investigated. A multilevel model with patients clustered within surgical teams and NHS Trusts was used to examine associations between LOS and a range of factors. RESULTS Over the study period the proportion of women having a mastectomy reduced from 58% to 52%. The proportion varied from 14% to 80% according to NHS Trust. LOS decreased by 21% from 1997/98 to 2004/05 (LOSratio = 0.79, 95%CI 0.77-0.80). BCS was associated with 33% shorter hospital stays compared to mastectomy (LOSratio = 0.67, 95%CI 0.66-0.68). Older age, advanced disease, presence of comorbidities, lymph node excision and reconstructive surgery were associated with increased LOS. Significant variation remained amongst Trusts and surgical teams. CONCLUSION The number of days spent in hospital after breast cancer surgery has continued to decline for several decades. The change from mastectomy to BCS accounts for only 9% of the overall decrease in LOS. Other explanations include the adoption of new techniques and practices, such as sentinel lymph node biopsy and early discharge. This study has identified wide variation in practice with substantial cost implications for the NHS. Further work is required to explain this variation

Analysis of motion during the breast clamping phase of mammography

Objectives: To measure paddle motion during the clamping phase of a breast phantom for a range of machine/paddle combinations. Methods: A deformable breast phantom was used to simulate a female breast. Twelve mammography machines from three manufacturers with twenty two flexible and twenty fixed paddles were evaluated. Vertical motion at the paddle was measured using two calibrated linear potentiometers. For each paddle, the motion in millimeters was recorded every 0.5 seconds for 40 seconds while the phantom was compressed with 80 N. Independent t-tests were used to determine differences in paddle motion between flexible and fixed, small and large, GE Senographe Essential and Hologic Selenia Dimensions paddles. Paddle tilt in the medial-lateral plane for each machine/paddle combination was calculated. Results: All machine/paddle combinations demonstrate highest levels of motion during the first 10s of the clamping phase. Least motion is 0.17±0.05 mm/10s (n=20) and the most is 0.51±0.15 mm/10s (n=80). There is a statistical difference in paddle motion between fixed and flexible (p<0.001), GE Senographe Essential and Hologic Selenia Dimensions paddles (p<0.001). Paddle tilt in the medial-lateral plane is independent of time and varied from 0.04° to 0.69°. Conclusions: All machine/paddle combinations exhibited motion and tilting and the extent varied with machine and paddle sizes and types. Advances in knowledge: This research suggests that image blurring will likely be clinically insignificant 4 seconds or more after the clamping phase commences