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K R Abrams

Publications and source records attributed to K R Abrams.

At least 19 recordsLinked to original sources
PubMed2007

An evaluation of bivariate random-effects meta-analysis for the joint synthesis of two correlated outcomes.

Often multiple outcomes are of interest in each study identified by a systematic review, and in this situation a separate univariate meta-analysis is usually applied to synthesize the evidence for each outcome independently; an alternative approach is a single multivariate meta-analysis model that utilizes any correlation between outcomes and obtains all the pooled estimates jointly. Surprisingly, multivariate meta-analysis is rarely considered in practice, so in this paper we illustrate the benefits and limitations of the approach to provide helpful insight for practitioners. We compare a bivariate random-effects meta-analysis (BRMA) to two independent univariate random-effects meta-analyses (URMA), and show how and why a BRMA is able to 'borrow strength' across outcomes. Then, on application to two examples in healthcare, we show: (i) given complete data for both outcomes in each study, BRMA is likely to produce individual pooled estimates with very similar standard errors to those from URMA; (ii) given some studies where one of the outcomes is missing at random, the 'borrowing of strength' is likely to allow BRMA to produce individual pooled estimates with noticeably smaller standard errors than those from URMA; (iii) for either complete data or missing data, BRMA will produce a more appropriate standard error of the pooled difference between outcomes as it incorporates their correlation, which is not possible using URMA; and (iv) despite its advantages, BRMA may often not be possible due to the difficulty in obtaining the within-study correlations required to fit the model. Bivariate meta-regression and further research priorities are also discussed.

Analysis of Variance↗
PubMed2007

Verifiable CPD paper: factors that influence the dental attendance pattern and maintenance of oral health for people with multiple sclerosis.

OBJECTIVE: To determine the impact of multiple sclerosis (MS) on patient attendance at dental practices and maintenance of oral health. DESIGN: A cross-sectional postal questionnaire-based study. SETTING: Leicestershire, United Kingdom. SUBJECTS AND METHODS: People with MS in Leicestershire identified from local health authority records (n = 476). MAIN OUTCOME MEASURES: Number registered at dental practice, frequency of attendance, issues and perspectives relating to attendance and maintenance of oral health. RESULTS: A response rate of 61% (n = 289) was obtained. When compared to the general population, a higher number of people with MS were registered with a dentist (49%:88%) and displayed more frequent practice attendance (71%:81%) in the past year. People with MS reported difficulties in attending a dentist and maintaining oral health, which were exacerbated by deterioration in general health. Problems relating to reduced personal mobility had the greatest impact on attendance. CONCLUSIONS: MS has a negative impact on perceived patient attendance and maintenance of oral health. Patients with a progressive disability could benefit greatly from the provision of preventive oral health care. The importance of seeking care earlier rather than later needs to be emphasised to both professionals and patients alike. Further efforts are required to increase awareness of the importance of oral health to the quality of life of people with MS and ensure that individuals with physical disabilities receive the same access to dental services as the able-bodied.

Architectural Accessibility↗
PubMed2007

Long-term prognosis in Crohn's disease: An epidemiological study of patients diagnosed more than 20 years ago in Cardiff.

AIM: To investigate the incidence of death in patients diagnosed with Crohn's disease in Cardiff over 20 years ago. METHODS: The Cardiff database of patients with Crohn's disease contains data on all patients diagnosed there since 1934. Patients (394) diagnosed before 1 January 1985 were traced and their mortality status on 31 December 2004 was established. RESULTS: The overall standardized mortality ratio (SMR) was 1.29 (95% CI 1.12-1.45) and it has not significantly changed since the 1970s. SMR decreases with age, from 16.95 (95% CI 14.99-18.91) for patients aged 10-19 years (although only one death) to 0.92 (95% CI 0.65-1.19) in those over 75 years. Kaplan-Meier analysis of age at death shows that patients diagnosed aged 10-26 years have median age at death of 58 years, those aged 27-52 years of 66 years, those aged 53-58 years of 74 years, and those over 59 years of 79 years. CONCLUSIONS: It shows a significantly raised SMR, not statistically changed since the 1970s and similar to other chronic conditions. Patients diagnosed younger have worse prognosis than those diagnosed later in life and a reduced life expectancy compared with the general population.

Age Factors↗
PubMed2006

Meta-analysis of mortality and cancer incidence among workers in the synthetic rubber-producing industry.

Production of synthetic rubber involves exposure to several potentially harmful chemicals. The authors carried out a systematic review and meta-analysis of cohort studies of workers in the rubber-producing industry. Data were obtained from computerized literature searches of several databases from their inception through December 2003. The reference lists of identified articles were inspected for further relevant articles. The authors conducted random-effects meta-analyses of log standardized mortality ratios (SMRs)/standardized incidence ratios. Heterogeneity between study results was explored through subgroup analyses and meta-regression on cohort demographic factors and study quality indicators. The authors identified 36 published articles reporting information on 31 different cohort groups. The meta-SMR was 0.86 (95% confidence interval (CI): 0.82, 0.91) for all-cause mortality (28 cohorts) and 0.94 (95% CI: 0.89, 1.01) for all malignant neoplasms (27 cohorts). Heterogeneity was observed for these endpoints and for the majority of disease-specific outcomes. Statistically significant excesses were observed for diabetes (meta-SMR=1.36, 95% CI: 1.17, 1.59) (five cohorts) and leukemia (meta-SMR=1.21, 95% CI: 1.03, 1.43) (16 cohorts), the latter particularly for persons working exclusively in nontire manufacturing (meta-SMR=1.70, 95% CI: 1.14, 2.54) (four cohorts). Excesses highlighted in previous narrative reviews were not substantiated. Interpretation of these results is complicated by substantial unexplainable heterogeneity; small excesses in specific mortality outcomes may have been disguised by the healthy worker effect.

Diabetes Mellitus↗
PubMed2006

Meta-analysis: colorectal and small bowel cancer risk in patients with Crohn's disease.

BACKGROUND: Crohn's disease is associated with small bowel cancer whilst risk of colorectal cancer is less clear. AIM: To ascertain the combined estimates of relative risk of these cancers in Crohn's disease. METHODS: MEDLINE was searched to identify relevant papers. Exploding references identified additional publications. When two papers reviewed the same cohort, the later study was used. RESULTS: Meta-analysis showed overall colorectal cancer relative risk in Crohn's disease as 2.5 (1.3-4.7), 4.5 (1.3-14.9) for patients with colonic disease and 1.1 (0.8-1.5) in ileal disease. Meta-regression showed reduction in relative risk over the past 30 years. Subgroup analysis showed Scandinavia had significantly lower colorectal cancer relative risk than the UK and North America. Cumulative risk analysis showed 10 years following diagnosis of Crohn's disease relative risk of colorectal cancer is 2.9% (1.5%-5.3%). Meta-analysis showed small bowel cancer relative risk in Crohn's disease is 33.2 (15.9-60.9). Small bowel cancer relative risk has not significantly reduced over the last 30 years. CONCLUSION: Relative risk of colorectal and small bowel cancers are significantly raised in Crohn's disease. Cumulative risk of colorectal cancer of 2.9% at 10 years suggests a potential benefit from routine screening. However, the value of screening requires rigorous appraisal.

Colitis↗
PubMed2006

Long-term prognosis in Crohn's disease: factors that affect quality of life.

BACKGROUND: There are many studies investigating quality of life in recently diagnosed patients and following surgery for Crohn's disease, but there are none investigating quality of life changes with disease duration. The response shift model suggests quality of life improves with time following diagnosis. AIM: To assess how well the model applies to patients with Crohn's disease. METHODS: The Cardiff Crohn's disease database contains data on all patients diagnosed there since 1934. Three hundred and ninety four patients diagnosed before 1 January 1985 were traced and the mortality status on 31 December 2004 established. Two hundred and eleven still living were sent quality of life questionnaires. Two hundred and eighty five questionnaires were sent to patients with varying disease duration attending out-patient clinics in Leicester. RESULTS: Eighty-nine valid replies were received from Cardiff, 63 from Leicester patients diagnosed over 20 years, 69 from Leicester patients diagnosed <10 years. There was no difference in quality of life between newly diagnosed and established patients. Of greatest concern was possible need for ostomy, uncertain nature of disease, and lack of energy. Stepwise regression showed that increased disease severity, older age and smoking adversely affect quality of life. DISCUSSION: Quality of life is equally poor in patients with established disease as in those newly diagnosed, and directly correlates with disease severity. The response shift model may not be applicable in Crohn's disease.

Adult↗
PubMed2006

Systematic review and meta-analysis of methods of diagnostic assessment for urinary incontinence.

AIMS: To evaluate the performance of all tests proposed for the diagnosis of urinary incontinence. METHODS: A systematic review and meta-analyses of the published literature of methods for diagnostic assessment of urinary incontinence. RESULTS: One hundred twenty-one papers were included in the full review [Martin et al., 2006]. The quality of reporting in the primary studies was poor which reduced the number of studies that could be included in the data analysis. The literature suggests that women with urodynamic stress incontinence (USI) can be correctly identified in primary care from clinical history alone with a sensitivity of 0.92 (95% C.I.: 0.91-0.93) and specificity of 0.56 (0.53-0.60). A clinical history for the diagnosis of detrusor overactivity (DO) was found to be 0.61 (0.57-0.65) sensitive and 0.87 (0.85-0.89) specific. Within secondary care imaging of leakage by ultrasound was found to be effective in the diagnosis of USI in women with a sensitivity of 0.89 (0.84-0.93) and specificity of 0.82 (0.73-0.89). CONCLUSIONS: Clinical interpretation of the results of the review is difficult because few studies could be synthesized and conclusions made. The published evidence suggests that a large proportion of women with USI can be correctly identified in primary care from history alone. Ultrasound offers a useful diagnostic tool which could be used prior to, and possibly instead of, multi-channel urodynamics in some circumstances. If a patient is to undergo urodynamic testing, multi-channel urodynamics is likely to give the most accurate result. Further primary studies adhering to STARD guidelines are required on commonly used tests.

Data Interpretation, Statistical↗
PubMed2006

Systematic review and evaluation of methods of assessing urinary incontinence.

OBJECTIVES: To identify and synthesise studies of diagnostic processes of urinary incontinence and to construct an economic model to examine the cost-effectiveness of simple, commonly used primary care tests. DATA SOURCES: The electronic databases MEDLINE (1966--2002), CINAHL (1982--2002) and EMBASE (1980--2002). REVIEW METHODS: Studies were selected and assessed using the Quality Assessment of Diagnostic Studies (QUADAS) tool. Studies that reported the results of applying the same diagnostic procedure using the same threshold value (cut-off) were pooled using a random effects meta-analysis model to produce pooled estimates of sensitivity, specificity and diagnostic odds ratio together with 95% confidence intervals. RESULTS: In total, 6009 papers were identified from the literature search, of which 129 were deemed relevant for inclusion in the review, and these papers compared two or more diagnostic techniques. The gold-standard diagnostic test for urinary incontinence with which each reference test was compared was multichannel urodynamics. In general, reporting in the primary studies was poor; there was a lack of literature in the key clinical areas and minimal literature dealing with diagnosis in men. Only a limited number of studies could be combined or synthesised, providing the following results when compared with multichannel urodynamics. A clinical history for diagnosing urodynamic stress incontinence (USI) in women was found to have a sensitivity of 0.92 and specificity of 0.56 and for detrusor overactivity (DO) a sensitivity of 0.61 and specificity of 0.87. For validated scales, question 3 of the Urogenital Distress Inventory was found to have a sensitivity of 0.88 and specificity of 0.60. Seven studies compared a pad test with multichannel urodynamics; however, four different pad tests were studied and therefore it was difficult to draw any conclusions about diagnostic accuracy. Of the four studies comparing urinary diary with multichannel urodynamics, only one presented data in a format that allowed sensitivity and specificity to be calculated. Their reported values of 0.88 and 0.83 suggest that a urinary diary may be effective in the diagnosis of DO in women. Examination of the incremental cost-effectiveness of three primary care tests used in addition to history found that the diary had the lowest cost-effectiveness ratio of between pound 35 and pound 77 per extra unit of effectiveness (or case diagnosed). Imaging by ultrasound to determine leakage was found to be effective in the diagnosis of USI in women, with a sensitivity of 0.94 and specificity of 0.83. CONCLUSIONS: This is the first systematic review of methods for diagnosing urinary incontinence. As reporting of the primary studies was poor, clinical interpretation was often difficult because few studies could be synthesised and conclusions made. The report found that a large proportion of women with USI can be correctly diagnosed in primary care from clinical history alone. On the basis of diagnosis the diary appears to be the most cost-effective of the three primary care tests (diary, pad test and validated scales) used in addition to clinical history. Ultrasound imaging may offer a valuable alternative to urodynamic investigation. The clinical stress test is effective in the diagnosis of USI. Adaptation of such a test so that it could be performed in primary care with a naturally filled bladder may prove clinically useful. If a patient is to undergo an invasive urodynamic procedure, multichannel urodynamics is likely to give the most accurate result in a secondary care setting. There is a dearth of literature on the diagnosis of urinary incontinence in men, with no studies meeting the study criteria for data extraction in the diagnosis of bladder outlet obstruction. There is a need for large-scale, high-quality primary studies evaluating the use of a number of diagnostic methods in a primary care setting to be undertaken so that the results of this systematic review can be verified or not. Such studies should include not only an assessment of clinical effectiveness, in this case diagnostic accuracy, but also an assessment of costs and quality of life/satisfaction to inform future health policy decisions. Studies carried out should be reported to a better standard. The recommendations of the Standards for Reporting Diagnostic Accuracy (STARD) initiative should be followed to ensure the accuracy and completeness of reporting design and results.

Diagnostic Tests, Routine↗
PubMed2005

The cost-effectiveness of influenza vaccination of healthy adults 50-64 years of age.

Influenza can cause significant morbidity and mortality. Influenza vaccination is an effective and safe strategy in the prevention of influenza. Currently the National Health Service (NHS) vaccinates 'at-risk' individuals only. This definition includes everyone over 65 years of age but excludes individuals 50-64 years of age unless they have an additional risk factor, such as underlying heart disease or lung disease. In order to examine the cost-effectiveness of an extension of the vaccination policy to include this age group we constructed an economic model to estimate the costs and benefits of vaccination from both a health service and a societal perspective. Data to populate the model was obtained from the literature and the outcome measure used was the quality adjusted life year (QALY). Influenza vaccination prevented an estimated 4508 cases (95% CI: 2431-7606) per 100,000 vaccinees per influenza season for a net cost to the NHS of pound653,221 (95% CI: 354,575-1,072,257). The net cost increased to pound1,139,069 (95% CI 27,052-2,030,473) when non-NHS costs were included and the estimated cost-per-QALY were pound6174 and pound10,766 for NHS and all costs respectively. Extension of the current immunisation policy has the potential to generate a significant health benefit at a comparatively low cost.

Cost-Benefit Analysis↗
PubMed2005

A year's trauma admissions and the effect of the weather.

PURPOSE OF THE STUDY: To study the admissions to a busy trauma unit on a day-by-day basis over a 1 year period, and to look for any correlation with local weather variation or temporal factors (day of the week, weekends/school holidays, etc.). METHOD: Admissions data for the Trauma Unit at the Leicester Royal Infirmary was collected from an administrative database and ward records for the calendar year of 1998. Admissions were split into four groups: all admissions, adult admissions, admissions for proximal femoral fractures (neck of femur (NOF)) and paediatric admissions. Weather information for the local area was obtained from the Meteorological Office. Details of school holidays were obtained from the local Education Department. The above variables were examined using Poisson regression analysis for their potential importance in explaining day-to-day variation in admission rates for the four groups. RESULTS: For adult and NOF admissions, none of the weather factors appeared to explain variation in incidence, only day of the week appears to be important, with the earlier part of the week yielding a highly statistically significant increase in the relative incidence of trauma admissions. For both paediatric and total admissions, a number of factors appear important, including maximum and minimum temperatures, hours of sunshine, day of the week and month of the year. Daily rainfall, significant weather and whether the day was a school day or school holiday did not appear to be important on univariate analysis. CONCLUSION: Trauma admissions are related to both weather and temporal factors. This may have implications both in terms of prevention and in planning of care provision in trauma units.

Adult↗
PubMed2004

Accuracy of a 12-lead electrocardiogram in screening patients with suspected heart failure for open access echocardiography: a systematic review and meta-analysis.

AIM: The aim of this study was to examine the usefulness of 12-lead electrocardiogram in screening patients with suspected heart failure for open access echocardiography. We carried out a systematic review and meta-analysis of published observational studies. Published studies were identified in the Medline and Embase databases, this was supplemented by key texts, personal reference collections and examining the cited references in the above sources. English language articles in which patients were referred from primary care with a presumptive diagnosis of heart failure to an open access echocardiography service were reviewed. We included studies that reported both electrocardiography findings and echocardiography as a reference standard. Primary outcome measures were sensitivity and specificity, meta-analysed simultaneously to produce a Summary Receiver Operating Characteristic (SROC) curve. RESULTS: Four trials were identified which satisfied the inclusion criteria, including 1419 people with a potential diagnosis of heart failure referred for open access echocardiography. Estimates of sensitivity and specificity varied greatly in individual studies. The area under the SROC curve was 0.84 (95% Cl: 0.33 to 1.00). CONCLUSION: A 12-lead electrocardiogram is an inadequate screening tool for identifying patients with suspected heart failure who require echocardiography. Further research is required to determine the usefulness of other screening strategies including B-type natriuretic peptide in screening patients with suspected heart failure who need referral for open access echocardiography.

Electrocardiography↗
PubMed2003

Reporting of prognostic markers: current problems and development of guidelines for evidence-based practice in the future.

Prognostic markers help to stratify patients for treatment by identifying patients with different risks of outcome (e.g. recurrence of disease), and are important tools in the management of cancer and many other diseases. Systematic review and meta-analytical approaches to identifying the most valuable prognostic markers are needed because (sometimes conflicting) evidence relating to markers is often published across a number of studies. To investigate the practicality of this approach, an empirical investigation of a systematic review of tumour markers for neuroblastoma was performed; 260 studies of prognostic markers were identified, which considered 130 different markers. The reporting of these studies was often inadequate, in terms of both statistical analysis and presentation, and there was considerable heterogeneity for many important clinical/statistical factors. These problems restricted both the extraction of data and the meta-analysis of results from the primary studies, limiting feasibility of the evidence-based approach.Guidelines for reporting the results of primary prognostic marker studies in cancer, and other diseases, are given in order to facilitate both the interpretation of individual studies and the undertaking of systematic reviews, meta-analysis and, ultimately, evidence-based practice. General availability of full individual patient data is a necessary step forward and would overcome the majority of problems encountered, including poorly reported summary statistics and variability in cutoff level, outcome assessed and adjustment factors used. It would also limit the problem of reporting bias, although publication bias will remain a concern until studies are prospectively registered. Such changes in practice would help important evidence-based reviews to be conducted in order to establish the most appropriate prognostic markers for clinical use, which should ultimately improve patient care.

Biomarkers, Tumor↗
PubMed2003

Meta-analysis of randomized clinical trials comparing open and laparoscopic inguinal hernia repair.

BACKGROUND: The aim was to conduct a meta-analysis of the randomized evidence to determine the relative merits of laparoscopic (LIHR) and open (OIHR) inguinal hernia repair. METHODS: A search of the Medline, Embase, Science Citation Index, Current Contents and PubMed databases identified all randomized clinical trials that compared OIHR and LIHR and were published in the English language between January 1990 and the end of October 2000. The meta-analysis was prepared in accordance with the Quality of Reporting of Meta-analyses (QUOROM) statement. The six outcome variables analysed were operating time, time to discharge from hospital, return to normal activity and return to work, postoperative complications and recurrence rate. Random effects meta-analyses were performed using odds ratios and weighted mean differences. RESULTS: Twenty-nine trials were considered suitable for meta-analysis. Some 3017 hernias were repaired laparoscopically and 2972 hernias were repaired using an open method in 5588 patients. For four of the six outcomes the summary point estimates favoured LIHR over OIHR; there was a significant reduction of 38 per cent in the relative odds of postoperative complications (odds ratio 0.62 (95 per cent confidence interval (c.i.) 0.46 to 0.84); P = 0.002), 4.73 (95 per cent c.i. 3.51 to 5.96) days in time to return to normal activity (P < 0.001), 6.96 (95 per cent c.i. 5.34 to 8.58) days in time to return to work (P < 0.001) and 3.43 (95 per cent c.i. 0.35 to 6.50) h in time to discharge from hospital (P = 0.029). There was a significant increase of 15.20 (95 per cent c.i. 7.78 to 22.63) min in the mean operating time for LIHR (P < 0.001). The relative odds of short-term recurrence were increased by 50 per cent for LIHR compared with OIHR, although this result was not statistically significant (odds ratio 1.51 (95 per cent c.i. 0.81 to 2.79); P = 0.194). CONCLUSION: LIHR was associated with earlier discharge from hospital, quicker return to normal activity and work, and significantly fewer postoperative complications than OIHR. However, the operating time was significantly longer and there was a trend towards an increase in the relative odds of recurrence after laparoscopic repair.

Hernia, Inguinal↗
PubMed2003

A systematic review of molecular and biological markers in tumours of the Ewing's sarcoma family.

The aims of this study were to perform the first systematic review of molecular and biological tumour markers in tumours of the Ewing's sarcoma family (ESFT), and evaluate the current evidence for their clinical use. A well-defined, reproducible search strategy was used to identify the relevant literature from 1966 to February 2000. Papers were independently assessed for tumour markers used in the screening, diagnosis, prognosis or monitoring of patients with ESFT. Eighty-four papers studying the use of 70 different tumour markers in ESFT's were identified. Low-quality, inconsistent reporting limited meta-analysis to that of prognostic data for 28 markers. Patients with tumours lacking S-100 protein expression have a better overall survival (OS) (hazard ratio (HR)=0.41, 95% confidence interval (CI) 0.19, 0.89) than those with expression; patients with high levels of serum LDH had a worse OS and disease-free survival (DFS) (OS: HR=2.92, CI 2.16, 3.94, DFS: HR=3.38, 95% CI 2.28, 4.99); patients with localised disease and tumours expressing type 1 EWS-FLI1 fusion transcripts had an improved DFS compared with those with other fusion transcript types (HR=0.17, 95% CI 0.079, 0.37). The knowledge base formed should facilitate more informative future research. Improved statistical reporting and large, multicentre prospective studies are advocated.

Biomarkers, Tumor↗
PubMed2002

Evaluation of a hip fracture risk score for assessing elderly women: the Melton Osteoporotic Fracture (MOF) study.

Risk assessment for osteoporotic fracture within a primary care context, in old age, has received little attention. We aimed to develop such a risk score and assess its feasibility and validity. This was a 100% population-based, prospective cohort study, with a minimum 5 1/2 year follow-up among women aged 70 years and over, set in a large single general practice in Melton Mowbray, Leicestershire, UK. The main outcome measures were hip fracture, death and migration. Baseline measures included calcaneal broadband ultrasound attenuation (BUA), reported falls, balance, previous fracture history, medical problems, visual acuity, foot problems, body size, lifestyle factors and cognitive impairment. Seventy percent of the sample (1289) participated, including those in residential accommodation. Independent predictors of hip fracture over 3 years were low weight, kyphosis, poor circulation in the foot, epilepsy, short-term use of steroids and poor trunk maneuver. Using the highest tertile, a risk score based on these variables identified 84% (95% CI: 70% to 98%) of the hip fractures with a specificity of 68% (95% CI: 65% to 71%). BUA did not independently predict hip fracture in women of this age group. This study shows that a combination of readily obtained risk factors can identify elderly women who will sustain a hip fracture in the next 3 years more accurately than bone measurements alone in younger women. It also suggests that a risk score approach to universal assessment in the elderly is a feasible proposition in the primary care setting.

Aged↗
PubMed2002

A comparison of summary patient-level covariates in meta-regression with individual patient data meta-analysis.

OBJECTIVES: To compare meta-analysis of summary study level data with the equivalent individual patient data (IPD) analysis when interest lies in identification of binary patient characteristics related to treatment efficacy. DESIGN: A simulation study comparing meta-regression with IPD analyses of randomized controlled trials. METHODS: Twenty-seven different meta-analysis situations were simulated with 1000 repetitions in each case. The following parameters were varied: (1) the treatment effect magnitude for different patient risk groups; (2) sample sizes of individual studies; and (3) number of studies. The meta-regression and IPD results were then compared for each situation. RESULTS: The statistical power of meta-regression was dramatically and consistently lower than that of IPD analysis, with little agreement between the parameter estimates obtained from the two methods. Only in meta-analyses of large numbers of large trials, did meta-regression detect differential treatment effects between risk groups with any consistency. CONCLUSIONS: Meta-analysis of summary data may be adequate when estimating a single pooled treatment effect or investigating study level characteristics. However, when interest lies in investigating whether patient characteristics are related to treatment, IPD analysis will generally be necessary to discover any such relationships. In these situations practitioners should try to obtain individual-level data.

Humans↗