ReviewBMC medical research methodology2009
Calculation of NNTs in RCTs with time-to-event outcomes: a literature review.
Review in BMC medical research methodology, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
14 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Systematic review of reporting benefits and harms of surgical interventions in randomized clinical trials.BJS open · 2020Pooled it
- Utility of the number needed to treat in paediatric haematological cancer randomised controlled treatment trials: a systematic review.BMJ open · 2019Pooled it
- Effectiveness of cranberry capsules to prevent urinary tract infections in vulnerable older persons: a double-blind randomized placebo-controlled trial in long-term care facilities.Journal of the American Geriatrics Society · 2014Trial
- Comorbidity and mortality results from a randomized prostate cancer screening trial.Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2011Trial
- Strengths and pitfalls of NNT and NNH in early breast cancer escalation trials.Breast (Edinburgh, Scotland) · 2026Article
- Time-constant absolute effect measures for time-to-event outcomes.BMC medical research methodology · 2025Article
- Understanding number needed to treat (NNT): A practical guide for anaesthesia and critical care clinicians.Indian journal of anaesthesia · 2025Article
- Computing and interpreting the Number Needed to Treat for Cardiovascular Outcomes Trials : Perspective on GLP-1 RA and SGLT-2i therapies.Cardiovascular diabetology · 2020Article
- Number-needed-to-treat analysis of clinical progression in patients with metastatic castration-resistant prostate cancer in the STRIVE and TERRAIN trials.BMC urology · 2018Article
- Number needed to treat (NNT) in clinical literature: an appraisal.BMC medicine · 2017Article
- Article
- What is the true number needed to screen and treat to save a life with prostate-specific antigen testing?Journal of clinical oncology : official journal of the American Society of Clinical Oncology · 2011Article
- Using and Interpreting Adjusted NNT Measures in Biomedical Research.The open dentistry journal · 2010Article
- Number needed to treat for interleukin inhibitors approved for the treatment of moderate-to-severe plaque psoriasis in Italy.Global & regional health technology assessmentArticle
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThe number needed to treat (NNT) is a well-known effect measure for reporting the results of clinical trials. In the case of time-to-event outcomes, the calculation of NNTs is more difficult than in the case of binary data. The frequency of using NNTs to report results of randomised controlled trials (RCT) investigating time-to-event outcomes and the adequacy of the applied calculation methods are unknown.
methodsWe searched in PubMed for RCTs with parallel group design and individual randomisation, published in four frequently cited journals between 2003 and 2005. We evaluated the type of outcome, the frequency of reporting NNTs with corresponding confidence intervals, and assessed the adequacy of the methods used to calculate NNTs in the case of time-to-event outcomes.
resultsThe search resulted in 734 eligible RCTs. Of these, 373 RCTs investigated time-to-event outcomes and 361 analyzed binary data. In total, 62 articles reported NNTs (34 articles with time-to-event outcomes, 28 articles with binary outcomes). Of the 34 articles reporting NNTs derived from time-to-event outcomes, only 17 applied an appropriate calculation method. Of the 62 articles reporting NNTs, only 21 articles presented corresponding confidence intervals.
conclusionThe NNT is used as effect measure to present the results from RCTs with binary and time-to-event outcomes in the current medical literature. In the case of time-to-event data incorrect methods were frequently applied. Confidence intervals for NNTs were given in one third of the NNT reporting articles only. In summary, there is much room for improvement in the application of NNTs to present results of RCTs, especially where the outcome is time to an event.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.