scholarly journals Methodological systematic review recommends improvements to conduct and reporting when meta-analysing interrupted time series studies

Author(s):  
Elizabeth Korevaar ◽  
Amalia Karahalios ◽  
Simon L Turner ◽  
Andrew B Forbes ◽  
Monica Taljaard ◽  
...  
2008 ◽  
Vol 22 (4) ◽  
pp. 237-245 ◽  
Author(s):  
Corina Mihaela Chivu ◽  
Theodore H. Tulchinsky ◽  
Karla Soares-Weiser ◽  
Rony Braunstein ◽  
Mayer Brezis

Objective. We conducted a systematic review of studies designed to increase awareness of, knowledge about, and consumption of folic acid before and during pregnancy. Data sources. Studies were identified from Cochrane Library, Medline, and the references of primary studies and reviews. Study inclusion and exclusion criteria. Studies included randomized controlled trials, quasi-experimental interrupted time series studies, follow-up studies, case-control studies, and before-and-after studies, all of which were conducted between 1992 and 2005 on women ages 15 to 49 years and/or health professionals, evaluating awareness and/or knowledge and/or consumption of folic acid both before and after intervention. Studies were excluded if data were not presented both before and after intervention or were other outcomes than those mentioned here. Data extraction. Data were extracted in relation to characteristics of studies, participants, interventions, and outcomes. Data synthesis. Because of heterogeneity, we performed a narrative synthesis describing the direction and the size of effects. Results. On average, women's awareness increased from 60% to 72%, knowledge from 21% to 45%, and consumption from 14% to 23%. Conclusions. Interventions had a positive effect on folic acid intakes before and during pregnancy, although the average usage reached less than 25%. So what? Further research is needed to design more effective interventions to increase periconceptional use of folic acid.


2020 ◽  
Author(s):  
Simon L Turner ◽  
Andrew B Forbes ◽  
Amalia Karahalios ◽  
Monica Taljaard ◽  
Joanne E McKenzie

AbstractInterrupted time series (ITS) studies are frequently used to evaluate the effects of population-level interventions or exposures. To our knowledge, no studies have compared the performance of different statistical methods for this design. We simulated data to compare the performance of a set of statistical methods under a range of scenarios which included different level and slope changes, varying lengths of series and magnitudes of autocorrelation. We also examined the performance of the Durbin-Watson (DW) test for detecting autocorrelation. All methods yielded unbiased estimates of the level and slope changes over all scenarios. The magnitude of autocorrelation was underestimated by all methods, however, restricted maximum likelihood (REML) yielded the least biased estimates. Underestimation of autocorrelation led to standard errors that were too small and coverage less than the nominal 95%. All methods performed better with longer time series, except for ordinary least squares (OLS) in the presence of autocorrelation and Newey-West for high values of autocorrelation. The DW test for the presence of autocorrelation performed poorly except for long series and large autocorrelation. From the methods evaluated, OLS was the preferred method in series with fewer than 12 points, while in longer series, REML was preferred. The DW test should not be relied upon to detect autocorrelation, except when the series is long. Care is needed when interpreting results from all methods, given confidence intervals will generally be too narrow. Further research is required to develop better performing methods for ITS, especially for short series.


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