Denosumab for the prevention of osteoporotic fractures in postmenopausal women

This paper presents a summary of the evidence review group (ERG) report into denosumab for the prevention of osteoporotic fractures in postmenopausal women. Denosumab has been shown in a large randomised trial to reduce the frequency of osteoporotic fractures when given subcutaneously at 6-monthly intervals. Compared with placebo, the relative risks of clinical vertebral and hip fractures were 0.32 and 0.60, respectively. Clinical vertebral fractures occurred in 0.8% of women taking denosumab and 2.6% of control subjects. Hip fractures occurred in 1.2% of women on placebo and 0.7% on denosumab. The expected use is in women who cannot tolerate oral bisphosphonates. Other options in that situation include strontium ranelate and zoledronate, which, compared with placebo, also reduced the risk of clinical vertebral fractures [relative risk (RR) 0.65 and 0.23, respectively]. Zoledronate also significantly reduced the risk of hip fractures (RR 0.59). The ERG concluded that zoledronate was the main comparator. The relative cost-effectiveness of denosumab and zoledronate depends mainly on assumptions about costs of administration.

Denosumab for the prevention of osteoporotic fractures in post-menopausal women: a NICE single technology appraisal

The National Institute for Health and Clinical Excellence (NICE) invited the manufacturer of denosumab (Amgen Inc., UK) to submit evidence for the clinical and cost effectiveness of denosumab for the prevention of fragility fractures in post-menopausal women, as part of the Institute's single technology appraisal (STA) process. The University of Aberdeen Health Technology Assessment Group were commissioned to act as the Evidence Review Group (ERG); the role of the ERG being to appraise the manufacturer's submission and to produce an independent report. This article provides a description of the company submission, the ERG review and NICE's subsequent decisions. The manufacturer considered that denosumab would be appropriate for patients unable to take, comply with or tolerate oral bisphosphonates. Comparator treatments selected for the submission were, therefore, 'no treatment', raloxifene, strontium ranelate, intravenous zoledronic acid, intravenous ibandronate and teriparatide. The main effectiveness evidence for denosumab was derived from a large randomized controlled trial comparing denosumab with placebo. Given by subcutaneous injection at 6-monthly intervals for 3 years, denosumab reduced the incidence of hip fracture by 40%, and reduced the incidence of clinical vertebral fracture by 69%. An indirect treatment comparison was used to derive adjusted relative risk (RR) estimates for different types of fracture for each comparator versus placebo. The RRs (95% CI) applied for denosumab were 0.316 (0.208, 0.478) for clinical vertebral fracture, 0.605 (0.373, 0.983) for hip fracture and 0.842 (0.638, 1.110) for wrist fracture. Despite a number of concerns surrounding the methodology of the indirect comparison, the ERG was satisfied with the robustness of the effect estimates. The RR estimates were applied in a good-quality Markov model that took account of drug costs, administration and monitoring costs, costs associated with fractures, and long-term nursing home costs. Utility weights were used to adjust time spent in fracture states, allowing QALYs to be estimated. The base-case analysis was conducted for women aged 70 years with a T-score of -2.5 or less and no prior fracture, and women aged 70 years with a T-score of -2.5 or less with a prior fragility fracture. Subgroup analyses based on T-score and independent clinical risk factors were also undertaken. Applying a willingness-to-pay (WTP) threshold of £30 000 per QALY, the manufacturer's results suggested that denosumab would offer a cost-effective alternative to all treatment comparators for the primary and secondary prevention of fractures. The ERG was concerned about an assumption that denosumab would be administered in general practice at the average cost of two standard GP visits a year. As a result, the ERG requested some further sensitivity analysis and undertook some further modelling, applying an assumption that denosumab would be provided primarily in secondary care. This modification altered the cost effectiveness of denosumab versus 'no treatment' (in women with no prior fragility fracture) and zoledronic acid. The NICE Appraisal Committee concluded that, as a treatment option for the prevention of osteoporotic fractures, denosumab should be recommended only in post-menopausal women at increased risk of fracture who cannot comply with the special instructions for administering oral bisphosphonates, or have an intolerance of, or contraindication to, those treatments. For primary prevention, the Appraisal Committee also stipulated specific levels of fracture risk at which denosumab is recommended.

Insulin sensitisers in the treatment of non-alcoholic fatty liver disease: a systematic review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is closely linked with obesity and the prevalence of NAFLD is about 17% to 33% in the Western world. There is a strong association of NAFLD with insulin resistance and, hence, insulin sensitisers have been tried. This systematic review examined the clinical effectiveness of insulin sensitisers in patients with NAFLD, to help decide whether or not a trial or trials of the insulin sensitisers was necessary and also to explore whether or not non-invasive alternatives to liver biopsy were available that could be used in a large trial of the insulin sensitisers.

OBJECTIVE

To review the use of insulin sensitisers in the treatment of NAFLD.

REVIEW METHODS

A systematic review of the clinical effectiveness of metformin, rosiglitazone and pioglitazone was carried out, including reviews and randomised controlled trials (RCTs). Databases searched were MEDLINE, 1950 to June 2010; EMBASE, 1980 to June 2010; Science Citation Index Expanded, June 2010; Conference Proceedings Citation Index - Science June 2010; The Cochrane Library 2005-10. Abstracts were screened independently by two researchers. A narrative review of diagnostic methods was conducted.

RESULTS

Clinical effectiveness. We identified 15 RCTs (one available as abstract). Four papers explored efficacy of pioglitazone, one rosiglitazone, eight metformin; two compared metformin and rosiglitazone, although one used both metformin and rosiglitazone. The duration of most trials was between 6 and 12 months. Many trials had a small number of participants and the quality of the studies was mixed. Pioglitazone improved all parameters of liver histology. Metformin showed mixed results, with ultrasound changes in two studies showing some improvement in steatosis, whereas there were no changes in the other two. Metformin, however, showed no improvement in non-alcoholic steatohepatitis (NASH) stages. Metformin showed greater reduction in glycosylated haemoglobin (-0.23% to -1.2% vs -0.2% to -0.7%) and fasting plasma glucose (+0.05 to -3.19 mmol/l vs -0.17 to -1.11 mmol/l) compared with pioglitazone. Metformin led to weight reduction (-4.3 to -6.7 kg), whereas participants on pioglitazone gained weight (+2.5 to +4.7 kg). Alanine aminotransferase levels were reduced with both metformin and pioglitazone; however, the reduction in levels with pioglitazone was not different to that caused by vitamin E. Most studies suggested that metformin led to a significant reduction in insulin resistance. Diagnosis. Non-invasive methods of diagnosing NAFLD without liver biopsy, using combinations of clinical history, laboratory tests and ultrasound, have been explored, but so far liver biopsy is the only proven method of distinguishing simple steatosis from NASH. Transient elastography appears useful, but less so in obese individuals. Magnetic resonance spectroscopy shows promise, but is expensive and not readily available.

LIMITATIONS

Mixed quality of trials, with lack of detail as to how some trials were conducted. Many trials had small numbers of patients.

CONCLUSIONS

The main need for drug trials is at the NASH stage. However, at present, any trial in the more advanced forms of NAFLD would have to use liver biopsy. The highest priority for research may, therefore, be in the diagnosis of NAFLD, and the differentiation between steatosis and NASH. The newer agents, the glucagon-like peptide-1 analogues such as liraglutide, may be more worthy of a trial.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam

The T2K experiment observes indications of ν(μ) → ν(e) appearance in data accumulated with 1.43×10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm(23)(2)| = 2.4×10(-3)  eV(2), sin(2)2θ(23) = 1 and sin(2)2θ(13) = 0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10(-3), equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2θ(13) < 0.28(0.34) for δ(CP) = 0 and a normal (inverted) hierarchy.

Denosumab for the prevention of osteoporotic fractures in postmenopausal women

This paper presents a summary of the evidence review group (ERG) report into denosumab for the prevention of osteoporotic fractures in postmenopausal women. Denosumab has been shown in a large randomised trial to reduce the frequency of osteoporotic fractures when given subcutaneously at 6-monthly intervals. Compared with placebo, the relative risks of clinical vertebral and hip fractures were 0.32 and 0.60, respectively. Clinical vertebral fractures occurred in 0.8% of women taking denosumab and 2.6% of control subjects. Hip fractures occurred in 1.2% of women on placebo and 0.7% on denosumab. The expected use is in women who cannot tolerate oral bisphosphonates. Other options in that situation include strontium ranelate and zoledronate, which, compared with placebo, also reduced the risk of clinical vertebral fractures [relative risk (RR) 0.65 and 0.23, respectively]. Zoledronate also significantly reduced the risk of hip fractures (RR 0.59). The ERG concluded that zoledronate was the main comparator. The relative cost-effectiveness of denosumab and zoledronate depends mainly on assumptions about costs of administration.

Screening for hyperglycaemia in pregnancy: a rapid update for the National Screening Committee

BACKGROUND

Screening for gestational diabetes has long been a controversial topic. A previous Health Technology Assessment (HTA) report reviewed literature on screening for gestational diabetes mellitus (GDM) and assessed the case for screening against the criteria set by the National Screening Committee.

OBJECTIVE

To update a previous HTA report which reviewed the literature on screening for GDM by examining evidence that has emerged since that last report, including the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS), the Maternal and Fetal Medicine Units Network (MFMUN) trial and the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study. To review data on recent trends in maternal age at birth and on the prevalence of overweight and obesity and the effect on prevalence of GDM.

DATA SOURCES

A systematic review and meta-analysis of the literature was carried out. The bibliographic databases used were MEDLINE (1996 to January 2009), EMBASE (1996 to December 2009), the Cochrane Library 2008 issue 4, the Centre for Reviews and Dissemination database and the Web of Science.

REVIEW METHODS

For the review of treatment with oral drugs versus insulin, a full systematic review and meta-analysis was carried out. The results of the ACHOIS, MFMUN and HAPO studies were summarised and their implications discussed. Findings of a selection of other recent studies, relevant to the continuum issue, were summarised. Some recent screening studies were reviewed, including a particular focus on studies of screening earlier in pregnancy.

RESULTS

The HAPO results showed a linear relationship between plasma glucose and adverse outcomes - there is a continuum of risk with no clear threshold which could divide women into those with gestational diabetes and those without. There was good evidence from trials and the meta-analysis that women who fail to control hyperglycaemic in pregnancy on lifestyle measures alone can be safely and effectively be treated with oral agents, metformin or glibenclamide, rather than going directly to insulin. Evidence showed few differences in results between glibenclamide and insulin and metformin and insulin. The exceptions were that there was less maternal hypoglycaemia with glibenclamide, but less neonatal hypoglycaemia and lower birthweight with insulin, and there was less maternal weight gain with metformin. The ACHOIS and MFMUN trials showed reductions in perinatal complications among infants born to mothers who were provided with more intensive dietary advice, blood glucose monitoring and insulin when required. The HAPO study demonstrated adverse outcomes over a much wider range of blood glucose (BG) than the traditional definition of GDM. In the HAPO study, no one measure of BG came out as being clearly the best, although fasting plasma glucose (FPG) was as good as any, and had advantages of being more convenient than an oral glucose tolerance test (OGTT), but correlations between fasting and post-load levels were quite poor. Two screening strategies dominated; (1) selection by the American Diabetes Association criteria followed by the 75-g OGTT [incremental cost-effectiveness ratio (ICER) 3678 pounds], and (2) selection by high-risk ethnicity followed by the 75-g OGTT (ICER 21,739 pounds). Studies indicated that costs are about 1833 pounds higher for pregnancies complicated by gestational diabetes, suggesting that prevention would be worthwhile.

LIMITATIONS

Not all of the HAPO results have been published, and none of the reviewed economic studies resolved the most difficult issue - at what level of BG does intervention become cost-effective?

CONCLUSIONS

The evidence base has improved since the last HTA review in 2002. There is now good evidence for treatment of oral drugs instead of insulin and it looks increasingly as if FPG could be the test of choice. However some key uncertainties remain to be resolved, which can be done by further analysis of the already collected HAPO data and by using the UK model used in developing the NICE guidelines to assess the cost-effectiveness of intervention in each of the seven HAPO categories.

Images of paraffin monolayer crystals with perfect contrast: minimization of beam-induced specimen motion

Quantitative analysis of electron microscope images of organic and biological two-dimensional crystals has previously shown that the absolute contrast reached only a fraction of that expected theoretically from the electron diffraction amplitudes. The accepted explanation for this is that irradiation of the specimen causes beam-induced charging or movement, which in turn causes blurring of the image due to image or specimen movement. In this paper, we used three different approaches to try to overcome this image-blurring problem in monolayer crystals of paraffin. Our first approach was to use an extreme form of spotscan imaging, in which a single image was assembled on film by the successive illumination of up to 50,000 spots, each of a diameter of around 7 nm. The second approach was to use the Medipix II detector with its zero-noise readout to assemble a time-sliced series of images of the same area in which each frame from a movie with up to 400 frames had an exposure of only 500 electrons. In the third approach, we simply used a much thicker carbon support film to increase the physical strength and conductivity of the support. Surprisingly, the first two methods involving dose fractionation in space or time produced only partial improvements in contrast whereas the third approach produced many virtually perfect images, where the absolute contrast predicted from the electron diffraction amplitudes was observed in the images. We conclude that it is possible to obtain consistently almost perfect images of beam-sensitive specimens if they are attached to an appropriately strong and conductive support; however great care is needed in practice and the problem remains of how to best image ice-embedded biological structures in the absence of a strong, conductive support film.

Phase accuracy in high-resolution electron microscopy of trigonal and orthorhombic purple membrane

High-resolution images of orthorhombic purple membrane have been obtained by electron cryomicroscopy with spot-scan illumination, and the projection structure at 3.9 A resolution calculated after image processing and averaging of the data. Since the phases of the structure factors in the projection down the orthorhombic twofold axis should be either 0 or 180 degrees , this offers the first opportunity to make an independent test of the estimated accuracy of high-resolution phases obtained by electron microscopy. The results show the final phases are less accurate than previously estimated by a small factor (1.3). Careful comparison of the new orthorhombic structure to the known trigonal structure shows only small differences after account is taken of a slight difference in the tilt angle of the molecules in the two crystals. This is consistent with the available kinetic and spectroscopic data which show very small differences in behavior.

The clinical effectiveness of glucosamine and chondroitin supplements in slowing or arresting progression of osteoarthritis of the knee: a systematic review and economic evaluation

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of glucosamine sulphate/hydrochloride and chondroitin sulphate in modifying the progression of osteoarthritis (OA) of the knee.

DATA SOURCES

Electronic databases were searched from 1950 to 2008 and included: MEDLINE and PubMed; EMBASE; Cochrane Library (including Cochrane Systematic Reviews Database, CENTRAL, DARE, NHS EED and HTA databases); Allied and Complementary Medicine (AMED); National Research Register (NRR); Web of Science Proceedings; Current Controlled Trials; and Clinical Trials.gov. Other sources included bibliographies of retrieved papers, registered but unpublished trials, internet searches and the Food Standards Agency website.

REVIEW METHODS

A search was conducted for systematic reviews of randomised controlled trials (RCTs), which were used to identify RCTs of at least 12 months' duration and updated with searches for primary studies. A cost-effectiveness model was constructed using cohort simulation and drawing on available evidence. Sensitivity analysis was undertaken and value of information analysis conducted. A review of studies of mechanism of action was carried out to explore the biological plausibility of the preparations.

RESULTS

Five systematic reviews and one clinical guideline met the inclusion criteria. They reported inconsistent conclusions with only modest effects on reported pain and function. A reduction in joint space narrowing was more consistently observed, but the effect size was small and the clinical significance uncertain. A separate review of eight primary trials of > 12 months' duration showed evidence of statistically significant improvements in joint space loss, pain and function for glucosamine sulphate, but the clinical importance of these differences was not clear. In two studies of glucosamine sulphate, the need for knee arthroplasty was reduced from 14.5% to 6.3% at 8 years' follow-up. For other preparations of glucosamine, chondroitin and combination therapy, there was less evidence to support a clinical effect. Cost-effectiveness modelling was restricted to glucosamine sulphate. Over a lifetime horizon the incremental cost per quality-adjusted life-year (QALY) gain for adding glucosamine sulphate to current care was estimated to be 21,335 pounds. Deterministic sensitivity analysis suggested that the cost-effectiveness of glucosamine sulphate therapy was particularly dependent on the magnitude of the quality of life (QoL) gain, the change in knee arthroplasty probability with therapy and the discount rate. At a cost per QALY gained threshold of 20,000 pounds, the likelihood that glucosamine sulphate is more cost-effective than current care is 0.43, while at a threshold of 30,000 pounds, the probability rises to 0.73. Probabilistic sensitivity analysis showed that estimates were imprecise and subject to a degree of decision uncertainty. Value of information analysis demonstrated the need for further research. Several biologically plausible mechanisms of action for glucosamine sulphate and chondroitin were proposed.

CONCLUSIONS

There was evidence that glucosamine sulphate shows some clinical effectiveness in the treatment of OA of the knee. No trial data came from the UK and caution should be exercised in generalising the findings to the UK health-care setting. Cost-effectiveness was not conclusively demonstrated. There was evidence to support the potential clinical impact of glucosamine sulphate. The value of information analysis identified three research priorities: QoL, structural outcomes and knee arthroplasty. The biological mechanism of glucosamine sulphate and chondroitin remains uncertain and, in particular, the proposal that the active substance may be sulphate should be explored further.

Experimental observation of the improvement in MTF from backthinning a CMOS direct electron detector

The advantages of backthinning monolithic active pixel sensors (MAPS) based on complementary metal oxide semiconductor (CMOS) direct electron detectors for electron microscopy have been discussed previously; they include better spatial resolution (modulation transfer function or MTF) and efficiency at all spatial frequencies (detective quantum efficiency or DQE). It was suggested that a 'thin' CMOS detector would have the most outstanding properties [1-3] because of a reduction in the proportion of backscattered electrons. In this paper we show, theoretically (using Monte Carlo simulations of electron trajectories) and experimentally that this is indeed the case. The modulation transfer functions of prototype backthinned CMOS direct electron detectors have been measured at 300keV. At zero spatial frequency, in non-backthinned 700-mum-thick detectors, the backscattered component makes up over 40% of the total signal but, by backthinning to 100, 50 or 35mum, this can be reduced to 25%, 15% and 10%, respectively. For the 35mum backthinned detector, this reduction in backscatter increases the MTF by 40% for spatial frequencies between 0.1 and 1.0 Nyquist. As discussed in the main text, reducing backscattering in backthinned detectors should also improve DQE.

Detective quantum efficiency of electron area detectors in electron microscopy

Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel detector, and an experimental direct electron monolithic active pixel sensor (MAPS) detector. Film and CCD performance was measured at 120 and 300 keV, while results are presented for the Medipix2 at 120 keV and for the MAPS detector at 300 keV. In the case of film, the effects of electron backscattering from both the holder and the plastic support have been investigated. We also show that part of the response of the emulsion in film comes from light generated in the plastic support. Computer simulations of film and the MAPS detector have been carried out and show good agreement with experiment. The agreement enables us to conclude that the DQE of a backthinned direct electron MAPS detector is likely to be equal to, or better than, that of film at 300 keV.

Encouraging attendance at outpatient appointments: can we do more?

BACKGROUND AND AIMS

Non-attendance at new outpatient appointments is a challenge for health services. Patients with treatable morbidity may fail to receive care from which they would benefit, and scarce resources are wasted. Therefore, a literature review was undertaken to assess the effectiveness of appointment reminders as a means of increasing attendance and reducing 'Did not Attend' rates at new outpatient appointments.

METHODS

Electronic databases were interrogated using a combination of MeSH terms and truncated keywords. In addition, the reference lists of papers were studied to identify additional relevant material.

RESULTS

Telephone and postal reminders appear effective, particularly if received within a day of scheduled appointments. Postal reminders offering a reward for attendance, threatening sanctions for non-attendance, and providing information about the clinic appear more effective than standard reminders. No studies assessing the impact of measures including e-mail or text messaging were identified. Many studies were conducted in psychiatric settings outwith the United Kingdom raising issues of generalisability. In addition, no assessment of how initiatives impact on inequalities in service access were found.

CONCLUSIONS

There is scope to increase attendance and reduce non-attendance at outpatient appointments but initiatives should be piloted in conjunction with robust evaluative frameworks.

Reduction in young male suicide in Scotland

Background

Rates of suicide and undetermined death increased rapidly in Scotland in the 1980's and 1990's. The largest increases were in men, with a marked increase in rates in younger age groups. This was associated with an increase in hanging as a method of suicide. National suicide prevention work has identified young men as a priority group. Routinely collected national information suggested a decrease in suicide rates in younger men at the beginning of the 21^st century. This study tested whether this was a significant change in trend, and whether it was associated with any change in hanging rates in young men.

Methods

Joinpoint regression was used to estimate annual percentage changes in age-specific rates of suicide and undetermined intent death, and to identify times when the trends changed significantly. Rates of deaths by method in 15 – 29 year old males and females were also examined to assess whether there had been any significant changes in method use in this age group.

Results

There was a 42% reduction in rates in 15 – 29 year old men, from 42.5/100,000 in 2000 to 24.5/100,000 in 2004. A joinpoint analysis confirmed that this was a significant change. There was also a significant change in trend in hanging in men in this age group, with a reduction in rates after 2000. No other male age group showed a significant change in trend over the period 1980 – 2004. There was a smaller reduction in suicide rates in women in the 15 – 29 year old age group, with a reduction in hanging from 2002.

Conclusion

There has been a reduction in suicide rates in men aged 15 – 29 years, and this is associated with a significant reduction in deaths by hanging in this age group. It is not clear whether this is related to a change in method preference, or an overall reduction in suicidal behaviour, and review of self-harm data will be required to investigate this further.

Electronic detectors for electron microscopy

Due to the increasing popularity of electron cryo-microscopy (cryoEM) in the structural analysis of large biological molecules and macro-molecular complexes and the need for simple, rapid and efficient readout, there is a persuasive need for improved detectors. Commercial detectors, based on phosphor/fibre optics-coupled CCDs, provide adequate performance for many applications, including electron diffraction. However, due to intrinsic light scattering within the phosphor, spatial resolution is limited. Careful measurements suggest that CCDs have superior performance at lower resolution while all agree that film is still superior at higher resolution. Consequently, new detectors are needed based on more direct detection, thus avoiding the intermediate light conversion step required for CCDs. Two types of direct detectors are discussed in this review. First, there are detectors based on hybrid technology employing a separate pixellated sensor and readout electronics connected with bump bonds-hybrid pixel detectors (HPDs). Second, there are detectors, which are monolithic in that sensor and readout are all in one plane (monolithic active pixel sensor, MAPS). Our discussion is centred on the main parameters of interest to cryoEM users, viz. detective quantum efficiency (DQE), resolution or modulation transfer function (MTF), robustness against radiation damage, speed of readout, signal-to-noise ratio (SNR) and the number of independent pixels available for a given detector.

Electron imaging with Medipix2 hybrid pixel detector

The electron imaging performance of Medipix2 is described. Medipix2 is a hybrid pixel detector composed of two layers. It has a sensor layer and a layer of readout electronics, in which each 55 microm x 55 microm pixel has upper and lower energy discrimination and MHz rate counting. The sensor layer consists of a 300 microm slab of pixellated monolithic silicon and this is bonded to the readout chip. Experimental measurement of the detective quantum efficiency, DQE(0) at 120 keV shows that it can reach approximately 85% independent of electron exposure, since the detector has zero noise, and the DQE(Nyquist) can reach approximately 35% of that expected for a perfect detector (4/pi(2)). Experimental measurement of the modulation transfer function (MTF) at Nyquist resolution for 120 keV electrons using a 60 keV lower energy threshold, yields a value that is 50% of that expected for a perfect detector (2/pi). Finally, Monte Carlo simulations of electron tracks and energy deposited in adjacent pixels have been performed and used to calculate expected values for the MTF and DQE as a function of the threshold energy. The good agreement between theory and experiment allows suggestions for further improvements to be made with confidence. The present detector is already very useful for experiments that require a high DQE at very low doses.

Digitisation of electron microscope films: Six useful tests applied to three film scanners

A series of simple tests have been used to measure the performance of flat-bed film scanners suitable for digitisation of electron micrographs. Two of the film scanners evaluated are commercially available and one has been constructed in the laboratory paying special attention to the needs of the electron microscopist. The tests may be useful for others.

Changes in Scottish suicide rates during the Second World War

Background

It is believed that total reported suicide rates tend to decrease during wartime. However, analysis of suicide rates during recent conflicts suggests a more complex picture, with increases in some age groups and changes in method choice. As few age and gender specific analyses of more distant conflicts have been conducted, it is not clear if these findings reflect a change in the epidemiology of suicide in wartime. Therefore, we examined suicide rates in Scotland before, during and after the Second World War to see if similar features were present.

Methods

Data on deaths in Scotland recorded as suicide during the period 1931 – 1952, and population estimates for each of these years, were obtained from the General Register Office for Scotland. Using computer spreadsheets, suicide rates by gender, age and method were calculated. Forward stepwise logistic regression was used to assess the effect of gender, war and year on suicide rates using SAS V8.2.

Results

The all-age suicide rate among both men and women declined during the period studied. However, when this long-term decline is taken into account, the likelihood of suicide during the Second World War was higher than during both the pre-War and post-War periods. Suicide rates among men aged 15–24 years rose during the Second World War, peaking at 148 per million (41 deaths) during 1942 before declining to 39 per million (10 deaths) by 1945, while the rate among men aged 25–34 years reached 199 per million (43 deaths) during 1943 before falling to 66 per million (23 deaths) by 1946. This was accompanied by an increase in male suicides attributable to firearms and explosives during the War years which decreased following its conclusion.

Conclusion

All age male and female suicide rates decreased in Scotland during World War II. However, once the general background decrease in suicide rates over the whole period is accounted for, the likelihood of suicide among the entire Scottish population during the Second World War was elevated. The overall decrease in suicide rates concealed large increases in younger male age groups during the War years, and an increase in male suicides recorded as due to the use of firearms. We conclude that the effects of war on younger people, reported in recent conflicts in Central Europe, were also seen in Scotland during the Second World War. The results support the findings of studies of recent conflicts which have found a heterogeneous picture with respect to age specific suicide rates during wartime.

Prospective neurocognitive effects and quality of life (QOL) in patients with multiple brain metastases receiving whole brain radiation (WBRT) ± thalidomide on radiation therapy oncology group (RTOG) trial 0118

8589

Background: RTOG 0118 was a randomized trial of WBRT (37.5 Gy/15 fractions) ± thalidomide in patients (pts) with brain metastases, which showed no effect on survival (Knisely et al, ASCO, 2005). This analysis examined the relationship between neurocognitive progression (NCP) and QOL in patients on both arms. Methods: NCP was assessed with the Folstein Mini-Mental Status Exam (MMSE) and QOL with the Spitzer QOL Index (SQLI). Pts with MMSE scores below age/education adjusted cutoff levels were considered to have NCP. T-test and Chi-Square statistics were used to determine significant differences in NCP and QOL between the two treatment arms over time. Results: Of 176 pts, 88 and 92% had SQLI and MMSE scores at baseline (43% were below the MMSE cutoff). Baseline SQLI (but not MMSE) was a significant predictor for OS (p=0.034). From baseline, SQLI and MMSE compliance rates were 74 and 60% at 1–2 months (mo), 37 and 29% at 4 mo, and 21 and 19% at 6 months, respectively. While QOL was stable, those who failed to meet MMSE cutoffs increased by 60% by 6 mo, on both study arms. Although a weak correlation (r=.23) existed at baseline between QOL and MMSE for both the WBRT (0.04) and WBRT/thalidomide (0.058) arms, there was no correlation beyond baseline. Conclusions: Baseline QOL is a significant predictor of OS. While QOL remained essentially stable, the degree of neurocognitive decline (60%) over time is concerning. These findings suggest the importance of these outcome measures in pts with brain metastases and the need for interventions to conserve cognitive status. RTOG is developing a trial to study the role of preventive strategies for NCP in brain metastases.

No significant financial relationships to disclose.

A note on testing for intervention effects on binary responses

OBJECTIVES

In some circumstances controlled trials are not feasible and treatments can only be evaluated using clinical databases. Here we consider the situation where treatment is introduced at a particular calendar time and can only be evaluated by comparison with historical controls. In these circumstances Heuer and Abel recommended using change-point methods to search for change in characteristics over the whole study period rather than simply comparing treated and untreated patients. Their recommendation is to only conclude that the intervention had an effect if a change-point could be demonstrated close in time to the introduction of the new treatment. This reduces the risk of false positives caused by confounding changes in population characteristics or changes in patient management. For binary data we develop a method that follows their philosophy and apply it to an observational study in the treatment of pin sites after orthopaedic surgery.

METHODS

Tests for change in binomial probabilities based on Brownian bridge and Hansen's approximation for maximally selected chi(2) statistics are compared to an exact test by Worsley. The approximate method is generalized to logistic regression models allowing for covariates.

RESULTS

The agreement of the exact and approximate method is good for sample sizes of 100 or more. The actual test size of the Hansen approximate test allowing for covariates is close to the nominal level, whereas the Brownian bridge approximation is slightly conservative. The change in pin site treatment significantly reduces the risk of infection for both adults and children.

CONCLUSIONS

We consider the Hansen approximation to provide a very good and very simple method for obtaining the p-value when testing for a change in binary data event probabilities, with or without covariates.

Individual survival time prediction using statistical models

Doctors' survival predictions for terminally ill patients have been shown to be inaccurate and there has been an argument for less guesswork and more use of carefully constructed statistical indices. As statisticians, the authors are less confident in the predictive value of statistical models and indices for individual survival times. This paper discusses and illustrates a variety of measures which can be used to summarise predictive information available from a statistical model. The authors argue that models and statistical indices can be useful at the group or population level, but that human survival is so uncertain that even the best statistical analysis cannot provide single-number predictions of real use for individual patients.

General practitioners' concerns about childhood immunisation and suggestions for improving professional support and vaccine uptake

In recent years childhood vaccination has been vigorously debated. Professional and parental confidence in the measles, mumps and rubella (MMR) vaccine in particular has been shaken, as reflected by its decreased uptake. A semi-structured postal questionnaire survey of general practitioners (GPs) working in the Highland region of Scotland was undertaken to assess their views on vaccination issues. A 73% response rate was achieved. Of respondents 28% expressed concerns about the possible side effects of MMR. Of GPs 98% thought it was 'likely' that the benefits of the DTP-Hib, polio and men C vaccines outweighed the possible risks. For the first and second doses of MMR 92% and 86%, respectively, believed this to be true. Approximately three quarters of GPs described themselves 'very confident' in discussing the DTP-Hib vaccine with parents, compared with 57% for MMR. Some respondents were misinformed regarding the adverse events associated with the MMR vaccine. There is professional concern about MMR. Initiatives to support GPs in promoting vaccination in order to improve immunisation rates are discussed.

Clinical effectiveness and cost-effectiveness of clopidogrel and modified-release dipyridamole in the secondary prevention of occlusive vascular events: a systematic review and economic evaluation

OBJECTIVES

To examine the clinical effectiveness and cost-effectiveness of two alternative antiplatelet agents, clopidogrel and modified-release (MR)-dipyridamole, relative to prophylactic doses of aspirin for the secondary prevention of occlusive vascular events.

DATA SOURCES

Electronic databases.

REVIEW METHODS

A total of 2906 titles and abstracts were rigorously screened and 441 studies were assessed in detail. Two RCTs were identified. For the assessment of cost-effectiveness, eight reviews were identified. The results were presented in structured tables and as a narrative summary. No additional clinical effectiveness data were presented in either of two company submissions. All economic evaluations (including accompanying models) included in the company submissions were assessed. Following this analysis, if the existing models (company or published) were not sufficient, a de novo model or modified versions of the models were developed.

RESULTS

In the CAPRIE trial the point estimate for the primary outcome, i.e. ischaemic stroke, myocardial infarction (MI) or vascular death, favoured clopidogrel over aspirin, but the boundaries of the confidence intervals raise the possibility that clopidogrel is not more beneficial than aspirin. In terms of the secondary outcomes reported, there was a non-significant trend in favour of clopidogrel over aspirin but the boundaries of the confidence intervals on the relative risks all crossed unity. There was no difference in the number of patients ever reporting any bleeding disorder in the clopidogrel group compared with the aspirin group. The incidences of rash and diarrhoea were statistically significantly higher in the clopidogrel group than the aspirin group. Patients in the aspirin group had a higher incidence of indigestion/nausea/vomiting than patients in the clopidogrel group. Haematological adverse events were rare in both the clopidogrel and aspirin groups. No cases of thrombotic thrombocytopenic purpura were reported in either group. Treatment with MR-dipyridamole alone did not significantly reduce the risk of any of the primary outcomes reported in ESPS-2 compared with treatment with aspirin. ASA-MR-dipyridamole was significantly more effective than aspirin alone in patients with stroke or transient ischaemic attacks (TIAs) at reducing the outcome of stroke and marginally more effective at reducing stroke and/or death. Treatment with ASA-MR-dipyridamole did not statistically significantly reduce the risk of death compared to treatment with aspirin. The number of strokes was statistically significantly reduced in the ASA-MR-dipyridamole group compared with the MR-dipyridamole group. In terms of the other primary outcomes, stroke and/or death and death, the results favoured treatment with ASA-MR-dipyridamole but the findings were not statistically significant. There was no difference in the number of bleeding complications between the ASA-MR-dipyridamole and aspirin groups. The incidence of bleeding complications was significantly lower in the MR-dipyridamole treatment group. More patients in the MR-dipyridamole treatment groups experienced headaches compared to patients receiving treatment with aspirin alone. The York model assessed the cost-effectiveness of differing combinations of treatment strategies in four patient subgroups, under a number of different scenarios. The results of the model were sensitive to the assumptions made in the alternative scenarios, in particular the impact of therapy on non-vascular deaths.

CONCLUSIONS

Clopidogrel was marginally more effective than aspirin at reducing the risk of ischaemic stroke, MI or vascular death in patients with atherosclerotic vascular disease, however, it did not statistically significantly reduce the risk of vascular death or death from any cause compared with aspirin. There was no statistically significant difference in the number of bleeding complications experienced in the clopidogrel and aspirin groups. MR-dipyridamole in combination with aspirin was superior to aspirin alone at reducing the risk of stroke and marginally more effective at reducing the risk of stroke and/or death. Compared with treatment with MR-dipyridamole alone, MR-dipyridamole in combination with aspirin significantly reduced the risk of stroke. Treatment with MR-dipyridamole in combination with aspirin did not statistically significantly reduce the risk of death compared with aspirin. Compared with treatment with MR-dipyridamole alone, bleeding complications were statistically significantly higher in patients treated with aspirin and MR-dipyridamole in combination with aspirin. Due to the assumptions that have to be made, no conclusions could be drawn about the relative effectiveness of MR-dipyridamole, alone or in combination with aspirin, and clopidogrel from the adjusted indirect comparison. The following would apply for a cost of up to GBP20,000-40,000 per additional quality-adjusted life-year. For the stroke and TIA subgroups, ASA-MR-dipyridamole would be the most cost-effective therapy given a 2-year treatment duration as long as all patients were not left disabled by their initial (qualifying) stroke. For a lifetime treatment duration, ASA-MR-dipyridamole would be considered more cost-effective than aspirin as long as treatment effects on non-vascular deaths are not considered and all patients were not left disabled by their initial stroke. In patients left disabled by their initial stroke, aspirin is the most cost-effective therapy. Clopidogrel and MR-dipyridamole alone would not be considered cost-effective under any scenario. For the MI and peripheral arterial disease subgroups, clopidogrel would be considered cost-effective for a treatment duration of 2 years. For a lifetime treatment duration, clopidogrel would be considered more cost-effective than aspirin as long as treatment effects on non-vascular deaths are not considered. It is suggested that the combination of clopidogrel and aspirin should be evaluated for the secondary prevention of occlusive vascular events. Also randomised, direct comparisons of clopidogrel and MR-dipyridamole in combination with aspirin are required to inform the treatment of patients with a history of stroke and TIA, plus trials that compare treatment with clopidogrel and MR-dipyridamole for the secondary prevention of vascular events in patients who demonstrate a genuine intolerance to aspirin.