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

Abstract

Background Randomised controlled trials (RCTs) are considered the gold standard when evaluating the causal effects of healthcare interventions. When RCTs cannot be used (e.g. ethically difficult), the interrupted time series (ITS) design is a possible alternative. ITS is one of the strongest quasi-experimental designs. The aim of this methodological study was to describe how ITS designs were being used, the design characteristics, and reporting in the healthcare setting. Methods We searched MEDLINE for reports of ITS designs published in 2015 which had a minimum of two data points collected pre-intervention and one post-intervention. There was no restriction on participants, language of study, or type of outcome. Data were summarised using appropriate summary statistics. Results One hundred and sixteen studies were included in the study. Interventions evaluated were mainly programs 41 (35%) and policies 32 (28%). Data were usually collected at monthly intervals, 74 (64%). Of the 115 studies that reported an analysis, the most common method was segmented regression (78%), 55% considered autocorrelation, and only seven reported a sample size calculation. Estimation of intervention effects were reported as change in slope (84%) and change in level (70%) and 21% reported long-term change in levels. Conclusions This methodological study identified problems in the reporting of design features and results of ITS studies, and highlights the need for future work in the development of formal reporting guidelines and methodological work. Electronic supplementary material The online version of this article (10.1186/s12874-019-0777-x) contains supplementary material, which is available to authorized users.

Common Practices for Divorce Education

“…Effectiveness of the program would be assessed by comparing parents who were close to the cutoff who were not ordered to divorce education against those who were. An interrupted time series design (Hudson, Fielding, & Ramsay, 2019) of divorce education would be another promising study design. Consider a situation in which all divorcing parents in a county have some sort of assessment or metric of healthy co‐parenting conducted.…”

Effectiveness of Peer-Supervision on Paediatric Fever Treatment Among Registered Private Drug Sellers in East-Central Uganda: An Interrupted Time Series Analysis

“…To assess the effectiveness of peer supervision among drug sellers on appropriate treatment of children less than ve years of age with pneumonia symptoms, uncomplicated malaria and non-bloody diarrhoea, interrupted time series for multiple group analysis was conducted [29]. The ITSA method was the preferred choice for this this study because it was not possible to randomise peer supervision (the intervention) [30]. In addition we wanted to cater for policy shifts if they occurred during the study period-a major strength of using interrupted time series [31].…”

Methods used to meta-analyse results from interrupted time series studies: A methodological systematic review protocol

“…Our search strategy has been informed by previous publications that have reviewed ITS studies 14 , 15 , 19 . Reviews of ITS studies will be identified using terms adapted from the search strategies of these publications and then combined with terms to identify meta-analyses and systematic reviews.…”

“…Reviews of ITS studies will be identified using terms adapted from the search strategies of these publications and then combined with terms to identify meta-analyses and systematic reviews. As there is little consistency in the terminology used to describe ITS studies 15 , 16 , our search terms are intentionally broad to achieve greater search sensitivity. Terms will be searched both as free text in the titles, abstracts and keywords fields, and as MeSH terms (or equivalent) where applicable.…”