Analysing randomised controlled trials with missing data : Choice of approach affects conclusions

Copyright © 2012 Elsevier Inc. All rights reserved. PMID: 22265924 [PubMed - indexed for MEDLINE]Peer reviewedPostprin

Methodology and reporting characteristics of studies using interrupted time series design in healthcare

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors for the design of the study and collection, analysis, and interpretation of data and in writing the manuscript. The Health Services Research Unit, University of Aberdeen, is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.Peer reviewedPublisher PD

Long term outcomes of simple clinical risk stratification in management of differentiated thyroid cancer

WL Craig was supported by a Cameron Research Fellowship, NHS Grampian. The University of Aberdeen Health Services Research Unit is supported by a core grant from the Chief Scientist Office of the Scottish Government Health and Social Care Directorate. There are no declared conflicts of interest.Peer reviewedPostprin

Predicting missing quality of life data that were later recovered : an empirical comparison of approaches

Peer reviewedPostprin

Investigating the missing data mechanism in quality of life outcomes: a comparison of approaches

Background: Missing data is classified as missing completely at random (MCAR), missing at random (MAR) or missing not at random (MNAR). Knowing the mechanism is useful in identifying the most appropriate analysis. The first aim was to compare different methods for identifying this missing data mechanism to determine if they gave consistent conclusions. Secondly, to investigate whether the reminder-response data can be utilised to help identify the missing data mechanism. Methods: Five clinical trial datasets that employed a reminder system at follow-up were used. Some quality of life questionnaires were initially missing, but later recovered through reminders. Four methods of determining the missing data mechanism were applied. Two response data scenarios were considered. Firstly, immediate data only; secondly, all observed responses (including reminder-response). Results: In three of five trials the hypothesis tests found evidence against the MCAR assumption. Logistic regression suggested MAR, but was able to use the reminder-collected data to highlight potential MNAR data in two trials. Conclusion: The four methods were consistent in determining the missingness mechanism. One hypothesis test was preferred as it is applicable with intermittent missingness. Some inconsistencies between the two data scenarios were found. Ignoring the reminder data could potentially give a distorted view of the missingness mechanism. Utilising reminder data allowed the possibility of MNAR to be considered.The Chief Scientist Office of the Scottish Government Health Directorate. Research Training Fellowship (CZF/1/31

A self-help diet and physical activity intervention with dietetic support for weight management in men treated for prostate cancer:pilot study of the PRO-MAN randomised controlled trial

Acknowledgements: We thank the Urology consultants at Aberdeen Royal Infirmary and staff of the UCAN centre, especially Paul Mannion, for support with the conduct of the study and the CLAN centre staff for hosting intervention group meetings. Funding: HM carried out this work while in receipt of a PhD scholarship from the Government of Malaysia. We thank Cancer Research in Aberdeen and NE Scotland (CRANES) for financial support for the pedometers and weighing scales. LCAC and GMcN acknowledge support from the RESAS programme of the Scottish Government.Peer reviewedPublisher PD

Ocean processes at the Antarctic continental slope

The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An © 2014 The Authors

A review of RCTs in four medical journals to assess the use of imputation to overcome missing data in quality of life outcomes

Background: Randomised controlled trials (RCTs) are perceived as the gold-standard method for evaluating healthcare interventions, and increasingly include quality of life (QoL) measures. The observed results are susceptible to bias if a substantial proportion of outcome data are missing. The review aimed to determine whether imputation was used to deal with missing QoL outcomes. Methods: A random selection of 285 RCTs published during 2005/6 in the British Medical Journal, Lancet, New England Journal of Medicine and Journal of American Medical Association were identified. Results: QoL outcomes were reported in 61 (21%) trials. Six (10%) reported having no missing data, 20 (33%) reported ≤ 10% missing, eleven (18%) 11%–20% missing, and eleven (18%) reported >20% missing. Missingness was unclear in 13 (21%). Missing data were imputed in 19 (31%) of the 61 trials. Imputation was part of the primary analysis in 13 trials, but a sensitivity analysis in six. Last value carried forward was used in 12 trials and multiple imputation in two. Following imputation, the most common analysis method was analysis of covariance (10 trials). Conclusion: The majority of studies did not impute missing data and carried out a complete-case analysis. For those studies that did impute missing data, researchers tended to prefer simpler methods of imputation, despite more sophisticated methods being available.The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health Directorate. Shona Fielding is also currently funded by the Chief Scientist Office on a Research Training Fellowship (CZF/1/31)

The Lantern Vol. 42, No. 1, Fall 1975

• The House • The Empty Man • Time • Corporea • Take Me • Elements of Nature • Hope • Acclimation • Road to Elat • Sinai • Jerusalem • Fatman • Ode to Grand Rapids • Ode to Cora • The Apple Cart • Next Time You\u27re Down South • Star Wreck • Eulogy to John Doe • A Postal Preoccupation • The Interview May Be Real (But Don\u27t Bet On It) • Winter Eve • My Love • God\u27s Children • A View From a Hill • Freedom For Us • Sleep Demonhttps://digitalcommons.ursinus.edu/lantern/1107/thumbnail.jp