Design and analysis of pilot studies: recommendations for good practice

Pilot studies play an important role in health research, but they can be misused, mistreated and misrepresented. In this paper we focus on pilot studies that are used specifically to plan a randomized controlled trial (RCT). Citing examples from the literature, we provide a methodological framework in which to work, and discuss reasons why a pilot study might be undertaken. A well-conducted pilot study, giving a clear list of aims and objectives within a formal framework will encourage methodological rigour, ensure that the work is scientifically valid and publishable, and will lead to higher quality RCTs. It will also safeguard against pilot studies being conducted simply because of small numbers of available patients.

Pathways underlying neuroprogression in bipolar disorder: focus on inflammation, oxidative stress and neurotrophic factors

There is now strong evidence of progressive neuropathological processes in bipolar disorder (BD). On this basis, the current understanding of the neurobiology of BD has shifted from an initial focus on monoamines, subsequently including evidence of changes in intracellular second messenger systems and more recently to, incorporating changes in inflammatory cytokines, corticosteroids, neurotrophins, mitochondrial energy generation, oxidative stress and neurogenesis into a more comprehensive model capable of explaining some of the clinical features of BD. These features include progressive shortening of the inter-episode interval with each recurrence, occurring in consort with reduced probability of treatment response as the illness progresses. To this end, emerging data shows that these biomarkers may differ between early and late stages of BD in parallel with stage-related structural and neurocognitive alterations. This understanding facilitates identification of rational therapeutic targets, and the development of novel treatment classes. Additionally, these pathways provide a cogent explanation for the efficacy of seemingly diverse therapies used in BD, that appear to share common effects on oxidative, inflammatory and neurotrophic pathways.

The impact of outcome reporting bias in randomised controlled trials on a cohort of systematic reviews

OBJECTIVE

To examine the prevalence of outcome reporting bias-the selection for publication of a subset of the original recorded outcome variables on the basis of the results-and its impact on Cochrane reviews.

DESIGN

A nine point classification system for missing outcome data in randomised trials was developed and applied to the trials assessed in a large, unselected cohort of Cochrane systematic reviews. Researchers who conducted the trials were contacted and the reason sought for the non-reporting of data. A sensitivity analysis was undertaken to assess the impact of outcome reporting bias on reviews that included a single meta-analysis of the review primary outcome.

RESULTS

More than half (157/283 (55%)) the reviews did not include full data for the review primary outcome of interest from all eligible trials. The median amount of review outcome data missing for any reason was 10%, whereas 50% or more of the potential data were missing in 70 (25%) reviews. It was clear from the publications for 155 (6%) of the 2486 assessable trials that the researchers had measured and analysed the review primary outcome but did not report or only partially reported the results. For reports that did not mention the review primary outcome, our classification regarding the presence of outcome reporting bias was shown to have a sensitivity of 88% (95% CI 65% to 100%) and specificity of 80% (95% CI 69% to 90%) on the basis of responses from 62 trialists. A third of Cochrane reviews (96/283 (34%)) contained at least one trial with high suspicion of outcome reporting bias for the review primary outcome. In a sensitivity analysis undertaken for 81 reviews with a single meta-analysis of the primary outcome of interest, the treatment effect estimate was reduced by 20% or more in 19 (23%). Of the 42 meta-analyses with a statistically significant result only, eight (19%) became non-significant after adjustment for outcome reporting bias and 11 (26%) would have overestimated the treatment effect by 20% or more.

CONCLUSIONS

Outcome reporting bias is an under-recognised problem that affects the conclusions in a substantial proportion of Cochrane reviews. Individuals conducting systematic reviews need to address explicitly the issue of missing outcome data for their review to be considered a reliable source of evidence. Extra care is required during data extraction, reviewers should identify when a trial reports that an outcome was measured but no results were reported or events observed, and contact with trialists should be encouraged.

A taxonomy has been developed for outcomes in medical research to help improve knowledge discovery

Objectives

There is increasing recognition that insufficient attention has been paid to the choice of outcomes measured in clinical trials. The lack of a standardized outcome classification system results in inconsistencies due to ambiguity and variation in how outcomes are described across different studies. Being able to classify by outcome would increase efficiency in searching sources such as clinical trial registries, patient registries, the Cochrane Database of Systematic Reviews, and the Core Outcome Measures in Effectiveness Trials (COMET) database of core outcome sets (COS), thus aiding knowledge discovery.

Study Design and Setting

A literature review was carried out to determine existing outcome classification systems, none of which were sufficiently comprehensive or granular for classification of all potential outcomes from clinical trials. A new taxonomy for outcome classification was developed, and as proof of principle, outcomes extracted from all published COS in the COMET database, selected Cochrane reviews, and clinical trial registry entries were classified using this new system.

Results

Application of this new taxonomy to COS in the COMET database revealed that 274/299 (92%) COS include at least one physiological outcome, whereas only 177 (59%) include at least one measure of impact (global quality of life or some measure of functioning) and only 105 (35%) made reference to adverse events.

Conclusions

This outcome taxonomy will be used to annotate outcomes included in COS within the COMET database and is currently being piloted for use in Cochrane Reviews within the Cochrane Linked Data Project. Wider implementation of this standard taxonomy in trial and systematic review databases and registries will further promote efficient searching, reporting, and classification of trial outcomes.

Dopamine dysregulation syndrome: implications for a dopamine hypothesis of bipolar disorder

OBJECTIVE

Rational therapeutic development in bipolar is hampered by a lack of pathophysiological model. However, there is a wealth of converging data on the role of dopamine in bipolar disorder. This paper therefore examines the possibility of a dopamine hypothesis for bipolar disorder.

METHOD

A literature search was conducted using standard search engines Embase, PyschLIT, PubMed and MEDLINE. In addition, papers and book chapters known to the authors were retrieved and examined for further relevant articles.

RESULTS

Collectively, in excess of 100 articles were reviewed from which approximately 75% were relevant to the focus of this paper.

CONCLUSION

Pharmacological models suggest a role of increased dopaminergic drive in mania and the converse in depression. In Parkinson's disease, administration of high-dose dopamine precursors can produce a 'maniform' picture, which switches into a depressive analogue on withdrawal. It is possible that in bipolar disorder there is a cyclical process, where increased dopaminergic transmission in mania leads to a secondary down regulation of dopaminergic receptor sensitivity over time. This may lead to a period of decreased dopaminergic transmission, corresponding with the depressive phase, and the repetition of the cycle. This model, if verified, may have implications for rational drug development.

Cost of illness of inflammatory bowel disease in the UK: a single centre retrospective study

BACKGROUND AND AIMS

The potentially high costs of care associated with inflammatory bowel disease (IBD) are recognised but we have little knowledge of the scale, profile, or determinants of these costs in the UK. This study aimed to describe costs of illness for a group of IBD patients and determine factors associated with increased healthcare costs.

SETTING

A university hospital serving a target population of approximately 330 000.

PATIENTS AND METHODS

A six month cohort of IBD patients receiving any form of secondary care was identified, comprising 307 cases of ulcerative (or indeterminate) colitis and 172 cases of Crohn's disease. Demographic and clinical data were abstracted from clinical records and individual resource use was itemised for all attributable costs (including extraintestinal manifestations). Item costs were derived from national and local sources. Cost data were expressed as mean six month costs per patient (with 95% confidence interval (CI)) obtained using non-parametric bootstrapping. Determinants of cost were analysed using generalised linear regression modelling. A postal survey of patients was undertaken to examine indirect costs, out of pocket expenses, and primary care visits.

RESULTS

Inpatient services (medical and/or surgical) were required by 67 patients (14%) but accounted for 49% of total secondary care costs. Drug costs accounted for less than a quarter of total costs. Individual patient costs ranged from 73 to 33,254 UK pounds per six months. Mean (95% CI) six month costs per patient were 1256 UK pounds ( 988 pounds, 1721 pounds) for colitis and 1652 UK pounds (1221 pounds, 2239 pounds) for Crohn's disease. Hospitalisation, disease severity grade, and disease extent correlated positively with cost of illness but costs were independent of age or sex. Compared with quiescent cases of IBD, disease relapse was associated with a 2-3-fold increase in costs for non-hospitalised cases and a 20-fold increase in costs for hospitalised cases. Survey data suggested average six month costs were < 30 UK pounds per patient for primary care visits (both diseases) and median loss of earnings were 239 UK pounds for colitis and 299 UK pounds for Crohn's disease.

CONCLUSIONS

This study represents the first detailed characterisation of the scale and determinants of costs of illness for IBD in a British hospital. Hospitalisation affected a minority of sufferers but accounted for half of the total direct costs falling on the healthcare system.

Minimal access retroperitoneal pancreatic necrosectomy: improvement in morbidity and mortality with a less invasive approach

OBJECTIVE

Comparison of minimal access retroperitoneal pancreatic necrosectomy (MARPN) versus open necrosectomy in the treatment of infected or nonresolving pancreatic necrosis.

SUMMARY OF BACKGROUND DATA

Infected pancreatic necrosis may lead to progressive organ failure and death. Minimal access techniques have been developed in an attempt to reduce the high mortality of open necrosectomy.

METHODS

This was a retrospective analysis on a prospective data base comprising 189 consecutive patients undergoing MARPN or open necrosectomy (August 1997 to September 2008). Outcome measures included total and postoperative ICU and hospital stays, organ dysfunction, complications and mortality using an intention to treat analysis.

RESULTS

Overall 137 patients underwent MARPN versus open necrosectomy in 52. Median (range) age of the patients was 57.5 (18-85) years; 118 (62%) were male. A total of 131 (69%) patients were tertiary referrals, with a median time to transfer from index hospital of 19 (2-76) days. Etiology was gallstones or alcohol in 129 cases (68%); 98 of 168 (58%) patients had a positive culture at the first procedure. Of the 137 patients, 34 (31%) had postoperative organ failure in the MARPN group, and 39 of 52 (56%) in the open group (P<0.0001); 59/137 (43%) versus 40/52 (77%), respectively, required postoperative ICU support (P<0.0001). Of the 137 patients 75 (55%) had complications in the MARPN group and 42 of 52 (81%) in the open group (P=0.001). There were 26 (19%) deaths in the MARPN group and 20 (38%) following open procedure (P=0.009). Age (P<0.0001), preoperative multiorgan failure (P<0.0001), and surgical procedure (MARPN, P=0.016) were independent predictors of mortality.

CONCLUSION

This study has shown significant benefits for a minimal access approach including fewer complications and deaths compared with open necrosectomy.

Effects of incomplete pulmonary gas exchange on VO2 max

Recent evidence suggests that heavy exercise may lower the percentage of O2 bound to hemoglobin (%SaO2) by greater than or equal to 5% below resting values in some highly trained endurance athletes. We tested the hypothesis that pulmonary gas exchange limitations may restrict VO2max in highly trained athletes who exhibit exercise-induced hypoxemia. Twenty healthy male volunteers were divided into two groups according to their physical fitness status and the demonstration of exercise-induced reductions in %SaO2 less than or equal to 92%: 1) trained (T), mean VO2max = 56.5 ml.kg-1.min-1 (n = 13) and 2) highly trained (HT) with maximal exercise %SaO2 less than or equal to 92%, mean VO2max = 70.1 ml.kg-1.min-1 (n = 7). Subjects performed two incremental cycle ergometer exercise tests to determine VO2max at sea level under normoxic (21% O2) and mild hyperoxic conditions (26% O2). Mean %SaO2 during maximal exercise was significantly higher (P less than 0.05) during hyperoxia compared with normoxia in both the T group (94.1 vs. 96.1%) and the HT group (90.6 vs. 95.9%). Mean VO2max was significantly elevated (P less than 0.05) during hyperoxia compared with normoxia in the HT group (74.7 vs. 70.1 ml.kg-1.min-1). In contrast, in the T group, no mean difference (P less than 0.05) existed between treatments in VO2max (56.5 vs. 57.1 ml.kg-1.min-1). These data suggest that pulmonary gas exchange may contribute significantly to the limitation of VO2max in highly trained athletes who exhibit exercise-induced reductions in %SaO2 at sea level.(ABSTRACT TRUNCATED AT 250 WORDS)

History of illness prior to a diagnosis of bipolar disorder or schizoaffective disorder

BACKGROUND

There are obstacles to early identification of bipolar disorder. Identifying and treating illness early in its time course may be associated with a better prognosis.

METHODS

A questionnaire was administered at interview, when the participant was euthymic, to participants (n=240) enrolled in the Bipolar Comprehensive Outcomes Study (BCOS). Information was collected about the sequential timeline of specific symptoms of mental illness up to when they first received a diagnosis of Bipolar Disorder or Schizoaffective Disorder.

RESULTS

Any symptoms of mental illness were first experienced at 17.5 years (median; Inter Quartile Range (IQR) 13.8-24.3; n=216) and mood swings at 18.0 years (IQR 14-25; n=197). Symptoms of depression were experienced at 18.0 years (IQR 14-25; n=197), a full episode of depression at 21.2 years (IQR 17-28.5; n=200), symptoms of mania at 21.0 years (IQR 16.8-29.5; n=212) and a full episode of mania at 24.1 years (IQR 19-30.5; n=205). Medical treatment was sought at 24.0 years (IQR 19-31.5; n=217). Participants received a diagnosis of Bipolar Disorder or Schizoaffective Disorder at 30.0 years (IQR 23-37.3; n=215). Having had a previous diagnosis other than Bipolar Disorder or Schizoaffective Disorder was reported by 120 of 216 participants who answered this question, most commonly unipolar depression (26.6%). Diagnostic delay was greater in individuals with early onset disorder.

CONCLUSIONS

Participants typically experience a long sequential course of symptoms, episodes, treatments and diagnosis. The polarity of onset is most commonly depressive, and subthreshold symptoms tend to precede threshold symptoms of both polarities.

LIMITATIONS

Data were collected retrospectively.

Alemtuzumab in Combination With Methylprednisolone Is a Highly Effective Induction Regimen for Patients With Chronic Lymphocytic Leukemia and Deletion of TP53: Final Results of the National Cancer Research Institute CLL206 Trial

Purpose

In chronic lymphocytic leukemia (CLL), TP53 deletion/mutation is strongly associated with an adverse outcome and resistance to chemotherapy-based treatment. In contrast, TP53 defects are not associated with resistance to the anti-CD52 monoclonal antibody alemtuzumab or methylprednisolone. In an attempt to improve the treatment of TP53-defective CLL, a multicenter phase II study was developed to evaluate alemtuzumab and methylprednisolone in combination.

Patients and Methods

Thirty-nine patients with TP53-deleted CLL (17 untreated and 22 previously treated) received up to 16 weeks of treatment with alemtuzumab 30 mg three times a week and methylprednisolone 1.0 g/m2 for five consecutive days every 4 weeks. Antimicrobial prophylaxis consisted of cotrimoxazole, itraconazole, and aciclovir (or valganciclovir for asymptomatic cytomegalovirus viremia). The primary end point was response as assigned by an end-point review committee. Secondary end points were safety, progression-free survival (PFS) and overall survival (OS).

Results

The overall response rate, complete response rate (including with incomplete marrow recovery), median PFS, and median OS were 85%, 36%, 11.8 months, and 23.5 months, respectively, in the entire cohort and 88%, 65%, 18.3 months, and 38.9 months, respectively, in previously untreated patients. Grade 3 to 4 hematologic and glucocorticoid-associated toxicity occurred in 67% and 23% of patients, respectively. Grade 3 to 4 infection occurred in 51% of the overall cohort and in 29% of patients less than 60 years of age. Treatment-related mortality was 5%.

Conclusion

Alemtuzumab plus methypredisolone is the most effective induction regimen hitherto reported in TP53-deleted CLL. The risk of infection is age related and, in younger patients, seems only marginally higher than that associated with rituximab, fludarabine, and cyclophosphamide.

Comparative efficacy of newer hypnotic drugs for the short-term management of insomnia: a systematic review and meta-analysis

OBJECTIVES

To compare the clinical effectiveness of zaleplon, zolpidem or zopiclone (Z-drugs) with either benzodiazepines licensed and approved for use in the UK for the short-term management of insomnia (diazepam, loprazolam, lorazepam, lormetazepam, nitrazepam, temazepam) or with each other.

METHODS

MEDLINE, EMBASE, PsycINFO, Science Citation Index/Web of Science were searched from 1966 to March 2003 and The Cochrane Library, reference lists of included studies and a number of psychopharmacology journals. Randomized controlled trials comparing either benzodiazepines with the Z-drugs or any two of the Z-drugs in patients with insomnia were included. Outcome measures included: sleep onset latency, total sleep duration, number of awakenings, quality of sleep, adverse events, tolerance, rebound insomnia and daytime alertness.

RESULTS AND CONCLUSIONS

Twenty four eligible studies were identified with a total study population of 3,909 (17 studies comparing a Z-drug with a benzodiazepine and 7 comparing a Z-drug). Insufficient or inappropriately reported data meant that meta-analysis was possible only for a small number of outcomes. There are few clear, consistent differences between the drugs. Some evidence suggests that zaleplon gives shorter sleep latency but shorter duration of sleep than zolpidem, reflecting the pharmacological profiles of the drugs.

Design and analysis of pilot studies: recommendations for good practice

Pilot studies play an important role in health research, but they can be misused, mistreated and misrepresented. In this paper we focus on pilot studies that are used specifically to plan a randomized controlled trial (RCT). Citing examples from the literature, we provide a methodological framework in which to work, and discuss reasons why a pilot study might be undertaken. A well-conducted pilot study, giving a clear list of aims and objectives within a formal framework will encourage methodological rigour, ensure that the work is scientifically valid and publishable, and will lead to higher quality RCTs. It will also safeguard against pilot studies being conducted simply because of small numbers of available patients.

A comparison of multivariable regression models to analyse cost data

RATIONALE, AIMS AND OBJECTIVES

Analysis of cost data is important in providing reliable information to aid budgeting decisions. Certain features of cost data, such as its typically highly skewed distribution and the need to estimate arithmetic mean costs in order to allow inferences to be made on total costs, make it difficult to analyse. Multivariable regression analysis is useful for estimating the influence of explanatory variables on cost in order to predict costs of future patients and allows for the control of variables which influence cost but whose distributions differ between comparison groups. This is especially important in the case of observational studies, where there may be no control over the balance of characteristics between the comparison groups.

METHOD

This paper compares the appropriateness of various multivariable models of cost data by examining regression diagnostics, using as an example data collected on costs incurred in the treatment of inflammatory bowel disease. The models compared are normal and bootstrapped multiple linear regression, median regression, gamma model with the log link and normal linear regression (NLR) of log costs.

RESULTS

Gamma modelling with the log link was found to be the most suitable model.

CONCLUSIONS

Bootstrapping was found to make very little difference to conclusions from the NLR model.

Pirfenidone in heart failure with preserved ejection fraction: a randomized phase 2 trial

In heart failure with preserved ejection fraction (HFpEF), the occurrence of myocardial fibrosis is associated with adverse outcome. Whether pirfenidone, an oral antifibrotic agent without hemodynamic effect, is efficacious and safe for the treatment of HFpEF is unknown. In this double-blind, phase 2 trial ( NCT02932566 ), we enrolled patients with heart failure, an ejection fraction of 45% or higher and elevated levels of natriuretic peptides. Eligible patients underwent cardiovascular magnetic resonance and those with evidence of myocardial fibrosis, defined as a myocardial extracellular volume of 27% or greater, were randomly assigned to receive pirfenidone or placebo for 52 weeks. Forty-seven patients were randomized to each of the pirfenidone and placebo groups. The primary outcome was change in myocardial extracellular volume, from baseline to 52 weeks. In comparison to placebo, pirfenidone reduced myocardial extracellular volume (between-group difference, -1.21%; 95% confidence interval, -2.12 to -0.31; P = 0.009), meeting the predefined primary outcome. Twelve patients (26%) in the pirfenidone group and 14 patients (30%) in the placebo group experienced one or more serious adverse events. The most common adverse events in the pirfenidone group were nausea, insomnia and rash. In conclusion, among patients with HFpEF and myocardial fibrosis, administration of pirfenidone for 52 weeks reduced myocardial fibrosis. The favorable effects of pirfenidone in patients with HFpEF will need to be confirmed in future trials.

Incidence of exercise induced hypoxemia in elite endurance athletes at sea level

Recent evidence suggests that exercise-induced hypoxemia (EIH) may occur in healthy trained endurance athletes. However, at present, no data exist to describe the regularity of EIH in athletes or non-athletes. Therefore, the purpose of the present investigation was to determine the incidence of EIH during exercise in healthy subjects varying in physical fitness. Subjects (N = 68) performed an incremental cycle ergometer test to volitional fatigue with percent arterial oxyhemoglobin saturation (%SaO2) measured min-by-min. For the purpose of data analysis subjects were divided into three groups according to their level of physical training: 1) untrained (N = 16), 2) moderately trained (N = 27), and 3) elite highly trained endurance athletes (N = 25). EIH was defined as a %SaO2 of less than or equal to 91% during exercise. EIH did not occur in any of the untrained subjects or the moderately trained subjects. However, EIH occurred in 52% of the highly trained endurance athletes tested and was highly reproducible (r = 0.95; P less than 0.05). These findings further confirm the existence of EIH in healthy highly trained endurance athletes and suggests a rather high incidence of EIH in this healthy population. Hence, it is important that the clinician or physiologist performing exercise testing in elite endurance athletes recognize that EIH can and does occur in the elite endurance athlete in the absence of lung disease.

The OMERACT-OARSI Core Domain Set for Measurement in Clinical Trials of Hip and/or Knee Osteoarthritis

OBJECTIVE

To update the 1997 OMERACT-OARSI (Outcome Measures in Rheumatology-Osteoarthritis Research Society International) core domain set for clinical trials in hip and/or knee osteoarthritis (OA).

METHODS

An initial review of the COMET database of core outcome sets (COS) was undertaken to identify all domains reported in previous COS including individuals with hip and/or knee OA. These were presented during 5 patient and health professionals/researcher meetings in 3 continents (Europe, Australasia, North America). A 3-round international Delphi survey was then undertaken among patients, healthcare professionals, researchers, and industry representatives to gain consensus on key domains to be included in a core domain set for hip and/or knee OA. Findings were presented and discussed in small groups at OMERACT 2018, where consensus was obtained in the final plenary.

RESULTS

Four previous COS were identified. Using these, and the patient and health professionals/researcher meetings, 50 potential domains formed the Delphi survey. There were 426 individuals from 25 different countries who contributed to the Delphi exercise. OMERACT 2018 delegates (n = 129) voted on candidate domains. Six domains gained agreement as mandatory to be measured and reported in all hip and/or knee OA clinical trials: pain, physical function, quality of life, and patient's global assessment of the target joint, in addition to the mandated core domain of adverse events including mortality. Joint structure was agreed as mandatory in specific circumstances, i.e., depending on the intervention.

CONCLUSION

The updated core domain set for hip and/or knee OA has been agreed upon. Work will commence to determine which outcome measurement instrument should be recommended to cover each core domain.

Blood lactate disappearance at various intensities of recovery exercise

Numerous studies have reported that following intense exercise the rate of blood lactate (La) disappearance is greater during continuous aerobic work than during passive recovery. Recent work indicates that a combination of high- and low-intensity work may be optimal in reducing blood La. We tested this hypothesis by measuring the changes in blood La levels following maximal exercise during four different recovery patterns. Immediately following 50 S of maximal work, subjects (n = 7) performed one of the following recovery treatments for 40 min: 1) passive recovery (PR); 2) cycling at 35% maximal O2 uptake (VO2 max) (35% R); 3) cycling at 65% VO2 max (65% R); 4) cycling at 65% for 7 min followed by cycling at 35% for 33 min (CR). The treatment order was counterbalanced with each subject performing all treatments. Serial blood samples were obtained throughout recovery treatments and analyzed for La. The rate of blood La disappearance was significantly greater (P less than 0.05) in both the 35% R and CR when compared with either the 65% R or PR. No significant difference (P greater than 0.05) existed in the rate of blood La disappearance between the 35% R and CR. These data do not support the hypothesis that exercise recovery at a combination of intensities is superior to a recovery involving continuous submaximal exercise in lowering blood La following maximal work.

Oxygen uptake kinetics in trained athletes differing in VO2max

Previous work has shown that when VO2 kinetics are compared for endurance trained athletes and untrained subjects, the highly trained athletes have a faster response time. However, it remains to be determined whether the more rapid adjustment of VO2 toward steady state in athletes is due to VO2max differences or training adaptation alone. One approach to this problem is to study the time course of VO2 kinetics at the onset of work in athletes who differ in VO2max but have similar training habits. Therefore, the purpose of these experiments was to compare the time course of VO2 kinetics at the onset of exercise in athletes with similar training routines but who differ in VO2max. Ten subjects (VO2max range 50-70 ml . kg-1 . min-1) performed 6-minutes of cycle ergometer exercise at approximately 50% VO2max. Ventilation and gas exchange were monitored by open circuit techniques. The data were modeled with a single component exponential function incorporating a time delay, (TD); delta VO2t = delta VO2ss (1-e-t-TD/tau), where tau is the time constant delta VO2t is the increase in VO2 at time t and delta VO2ss is the steady-rate increment above resting VO2. Kinetic analysis revealed a range of VO2 half times from 21.6 to 36.0 s across subjects with a correlation coefficient of r = -0.80 (p less than 0.05) between VO2max and VO2 half time. These data suggest that in highly trained individuals with similar training habits, those with a higher VO2max achieve a more rapid VO2 adjustment at the onset of work.

Nonadherence to treatment protocol in published randomised controlled trials: a review

This review aimed to ascertain the extent to which nonadherence to treatment protocol is reported and addressed in a cohort of published analyses of randomised controlled trials (RCTs). One hundred publications of RCTs, randomly selected from those published in BMJ, New England Journal of Medicine, the Journal of the American Medical Association and The Lancet during 2008, were reviewed to determine the extent and nature of reported nonadherence to treatment protocol, and whether statistical methods were used to examine the effect of such nonadherence on both benefit and harms analyses. We also assessed the quality of trial reporting of treatment protocol nonadherence and the quality of reporting of the statistical analysis methods used to investigate such nonadherence. Nonadherence to treatment protocol was reported in 98 of the 100 trials, but reporting on such nonadherence was often vague or incomplete. Forty-two publications did not state how many participants started their randomised treatment. Reporting of treatment initiation and completeness was judged to be inadequate in 64% of trials with short-term interventions and 89% of trials with long-term interventions. More than half (51) of the 98 trials with treatment protocol nonadherence implemented some statistical method to address this issue, most commonly based on per protocol analysis (46) but often labelled as intention to treat (ITT) or modified ITT (23 analyses in 22 trials). The composition of analysis sets for their benefit outcomes were not explained in 57% of trials, and 62% of trials that presented harms analyses did not define harms analysis populations. The majority of defined harms analysis populations (18 out of 26 trials, 69%) were based on actual treatment received, while the majority of trials with undefined harms analysis populations (31 out of 43 trials, 72%) appeared to analyse harms using the ITT approach. Adherence to randomised intervention is poorly considered in the reporting and analysis of published RCTs. The majority of trials are subject to various forms of nonadherence to treatment protocol, and though trialists deal with this nonadherence using a variety of statistical methods and analysis populations, they rarely consider the potential for bias introduced. There is a need for increased awareness of more appropriate causal methods to adjust for departures from treatment protocol, as well as guidance on the appropriate analysis population to use for harms outcomes in the presence of such nonadherence.

Cognitive effects of adjunctive N-acetyl cysteine in psychosis

BACKGROUND

Cognitive deficits are predictors of functional outcome in patients with psychosis. While conventional antipsychotics are relatively effective on positive symptoms, their impact on negative and cognitive symptoms is limited. Recent studies have established a link between oxidative stress and neurocognitive deficits in psychosis. N-acetylcysteine (NAC), a glutathione precursor with glutamatergic properties, has shown efficacy on negative symptoms and functioning in patients with schizophrenia and bipolar disorder, respectively. However, there are few evidence-based approaches for managing cognitive impairment in psychosis. The present study aims to examine the cognitive effects of adjunctive NAC treatment in a pooled subgroup of participants with psychosis who completed neuropsychological assessment in two trials of both schizophrenia and bipolar disorder.

METHOD

A sample of 58 participants were randomized in a double fashion to receive 2 g/day of NAC (n = 27) or placebo (n = 31) for 24 weeks. Attention, working memory and executive function domains were assessed. Differences between cognitive performance at baseline and end point were examined using Wilcoxon's test. The Mann-Whitney test was used to examine the differences between the NAC and placebo groups at the end point.

RESULTS

Participants treated with NAC had significantly higher working memory performance at week 24 compared with placebo (U = 98.5, p = 0.027).

CONCLUSIONS

NAC may have an impact on cognitive performance in psychosis, as a significant improvement in working memory was observed in the NAC-treated group compared with placebo; however, these preliminary data require replication. Glutamatergic compounds such as NAC may constitute a step towards the development of useful therapies for cognitive impairment in psychosis.

A role for glutathione in the pathophysiology of bipolar disorder and schizophrenia? Animal models and relevance to clinical practice

The tripeptide, glutathione (gamma-glutamylcysteinylglycine) is the primary endogenous free radical scavenger in the human body. When glutathione (GSH) levels are reduced there is an increased potential for cellular oxidative stress, characterised by an increase and accruement of reactive oxygen species (ROS). Oxidative stress has been implicated in the pathology of schizophrenia and bipolar disorder. This could partly be caused by alterations in dopaminergic and glutamatergic activity that are implicated in these illnesses. Glutamate and dopamine are highly redox reactive molecules and produce ROS during normal neurotransmission. Alterations to these neurotransmitter pathways may therefore increase the oxidative burden in the brain. Furthermore, mitochondrial dysfunction, as a source of oxidative stress, has been documented in both schizophrenia and bipolar disorder. The combination of altered neurotransmission and this mitochondrial dysfunction leading to oxidative damage may ultimately contribute to illness symptoms. Animal models have been established to investigate the involvement of glutathione depletion in aspects of schizophrenia and bipolar disorder to further characterise the role of oxidative stress in psychopathology. Stemming from preclinical evidence, clinical studies have recently shown antioxidant precursor treatment to be effective in schizophrenia and bipolar disorder, providing a novel clinical angle to augment often suboptimal conventional treatments.

Oral-facial-digital syndrome type 1 is another dominant polycystic kidney disease: clinical, radiological and histopathological features of a new kindred

BACKGROUND

Oral-facial-digital syndrome type 1 (OFD1) is a rare disorder comprising malformations of the face, oral cavity, hands, and feet. Polycystic kidney disease (PKD) is a more recently recognized feature of the syndrome.

SUBJECTS AND METHODS

We now report on the clinical, radiological and histopathological features of an OFD1 and PKD kindred with five affected members in three subsequent generations.

RESULTS

All patients were female and had accompanying PKD as assessed by ultrasound scans. The plasma creatinine was normal in three, but PKD caused end-stage renal failure in two of these individuals in the second and fifth decades. A histochemical analysis of renal tissue from one affected member of this kindred demonstrated a predominantly glomerulocystic kidney disease with a minor population of cysts derived from distal tubules as assessed by staining with Arachis hypogaea lectin. Cyst epithelia had a high level of mitosis as assessed by staining with antisera to proliferating cell nuclear antigen, and distal cysts overexpressed PAX2 protein, a potentially oncogenic transcription factor. We detected multiple pancreatic cysts in one member affected by OFD1 although there were no symptoms of pancreatic disease; this constitutes a novel radiological feature of the syndrome.

CONCLUSIONS

This kindred illustrates the inheritance pattern of OFD1 and its accompanying PKD. Although the renal disease superficially resembles ADPKD with macroscopic cysts and a dominant inheritance pattern, histology shows a predominance of glomerular cysts and the syndrome is X-linked, with affected males dying before birth. The recognition of the accompanying dysmorphic features is the key to a diagnosis of OFD1 in a female child or adult who presents with PKD.

Preoperative resolution of jaundice following biliary stenting predicts more favourable early survival in resected pancreatic ductal adenocarcinoma

INTRODUCTION

Despite the widespread use of endoscopic biliary stenting in patients presenting with potentially resectable pancreatic cancer, there is no general consensus regarding whether this represents a superior management approach over expeditious surgical intervention. The objective of this study was to investigate the influence of preoperative biliary stenting and resolution of jaundice on subsequent postoperative survival following resection for pancreatic cancer.

METHODS

155 patients undergoing partial pancreatoduodenectomy for pancreatic ductal adenocarcinoma between January 1997 and August 2007 were identified from a prospectively maintained database.

RESULTS

There was no survival difference when comparing patients undergoing preoperative biliary drainage (n = 130) with those who did not (n = 25) (log rank, P = 0.981). When analysing individual prognostic factors as continuous variables in univariate Cox analysis, lower albumin levels (P = 0.016), elevated alkaline phosphatase levels (P = 0.011) and elevated CRP levels (P = 0.021) were associated with poorer overall survival. Multivariable Cox regression demonstrated that both albumin (P = 0.008) and CRP (P = 0.038) remained significant independent predictors of overall survival alongside lymph node ratio (P = 0.018). Although preoperative bilirubin levels were not associated with overall survival when analysed as a continuous variable (Cox, P = 0.786), the presence of jaundice (i.e., bilirubin >35 micromol/l) at the time of surgery was a significant adverse predictor of early survival in patients undergoing preoperative biliary drainage (Breslow-Gehan-Wilcoxon, P = 0.013) and remained a significant predictor of early survival when included in a further Cox analysis with censoring of cases who survived beyond 6 months (Cox, P = 0.017).

CONCLUSION

These results suggest that the presence of jaundice at the time of resection has an adverse impact on early, but not overall, postoperative survival in pancreatic cancer patients undergoing preoperative biliary drainage.

Lower levels of physical activity in childhood associated with adult depression

Emerging evidence indicates that early life exposures influence adult health outcomes and there is cause to hypothesise a role for physical activity (PA) in childhood as a protective factor in adult depression. This study aimed to investigate the association between self-reported levels of PA in childhood and self-reported depressive illness. Lifetime depression and levels of physical activity (low/high) in childhood (<15 yr) were ascertained by self-report in 2152 adults (20-97 yr) participating in an ongoing epidemiological study in south-eastern Australia. Data were collected between 2000 and 2006. In this sample, 141 women (18.9%) and 169 men (12.0%) reported ever having a depressive episode. Low PA in childhood was associated with an increased risk of reporting depression in adulthood (OR=1.70, 95%CI=1.32-2.17, p<0.001). Adjustment for age, gender and adult PA attenuated the relationship somewhat (OR=1.35, 95%CI=1.01-1.78, p=0.04), however further adjustment for SES or country of birth did not affect this relationship. In this community-based study, lower levels of self-reported PA in childhood were associated with a 35% increase in odds for self-reported depression in adulthood. These results are consistent with the hypothesis that lower levels of PA in childhood may be a risk factor for adult depression.