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. 2018 Oct 24;18(1):115.
doi: 10.1186/s12874-018-0576-9.

A systematic survey shows that reporting and handling of missing outcome data in networks of interventions is poor

Loukia M Spineli  1 , Juan J Yepes-Nuñez  2   3 , Holger J Schünemann  2   4
Affiliations

A systematic survey shows that reporting and handling of missing outcome data in networks of interventions is poor

Loukia M Spineli et al. BMC Med Res Methodol. .

Abstract

Background: To provide empirical evidence about prevalence, reporting and handling of missing outcome data in systematic reviews with network meta-analysis and acknowledgement of their impact on the conclusions.

Methods: We conducted a systematic survey including all published systematic reviews of randomized controlled trials comparing at least three interventions from January 1, 2009 until March 31, 2017.

Results: We retrieved 387 systematic reviews with network meta-analysis. Description of missing outcome data was available in 63 reviews. Intention-to-treat analysis was the most prevalent method (71%), followed by missing outcome data investigated as secondary outcome (e.g., acceptability) (40%). Bias due to missing outcome data was evaluated in half the reviews with explicit judgments in 18 (10%) reviews. Only 88 reviews interpreted their results acknowledging the implications of missing outcome data and mostly using the network meta-analysis results on missing outcome data as secondary outcome. We were unable to judge the actual strategy applied to deal with missing outcome data in 65% of the reviews due to insufficient information. Six percent of network meta-analyses were re-analyzed in sensitivity analysis considering missing outcome data, while 4% explicitly justified the strategy for dealing with missing outcome data.

Conclusions: The description and handling of missing outcome data as well as the acknowledgment of their implications for the conclusions from network meta-analysis are deemed underreported.

Keywords: Empirical research; Intention-to-treat analysis; Missing outcome data; Network meta-analysis; Systematic review.

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Conflict of interest statement

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Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1
Fig. 1
Flow diagram of systematic reviews with network meta-analysis. ITC, indirect treatment comparison; MA, meta-analysis; NMA, network meta-analysis; RCT, randomized controlled trial
Fig. 2
Fig. 2
Bubble chart of 387 systematic reviews with network meta-analysis by year of publication and health specialty
Fig. 3
Fig. 3
Mosaic plot of 387 systematic reviews with network meta-analysis to visualize the frequency of incorporation of GRADE approach by year of publication. GRADE, Grading of Recommendations, Assessment, Development and Evaluation
Fig. 4
Fig. 4
Stacked bar chart of intervention-comparator type and network shape (left) and a stacked bar chart of outcome type and effect measure in 273 selected network meta-analyses (right)
See this image and copyright information in PMC

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