Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Randomized Controlled Trial
. 2013 Apr;27(4):183-8.
doi: 10.1097/BOT.0b013e3182647e0e.

(Sample) size matters! An examination of sample size from the SPRINT trial study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures

SPRINT Investigators  1 ; Mohit Bhandari, Paul Tornetta 3rd, Shelly-Ann Rampersad, Sheila Sprague, Diane Heels-Ansdell, David W Sanders, Emil H Schemitsch, Marc Swiontkowski, Stephen Walter
Collaborators, Affiliations
Randomized Controlled Trial

(Sample) size matters! An examination of sample size from the SPRINT trial study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures

SPRINT Investigators et al. J Orthop Trauma. 2013 Apr.

Abstract

Introduction: Inadequate sample size and power in randomized trials can result in misleading findings. This study demonstrates the effect of sample size in a large clinical trial by evaluating the results of the Study to Prospectively evaluate Reamed Intramedullary Nails in Patients with Tibial fractures (SPRINT) trial as it progressed.

Methods: The SPRINT trial evaluated reamed versus unreamed nailing of the tibia in 1226 patients, and in open and closed fracture subgroups (N = 400 and N = 826, respectively). We analyzed the reoperation rates and relative risk comparing treatment groups at 50, 100, and then increments of 100 patients up to the final sample size. Results at various enrollments were compared with the final SPRINT findings.

Results: In the final analysis, there was a statistically significant decreased risk of reoperation with reamed nails for closed fractures (relative risk reduction 35%). Results for the first 35 patients enrolled suggested that reamed nails increased the risk of reoperation in closed fractures by 165%. Only after 543 patients with closed fractures were enrolled did the results reflect the final advantage for reamed nails in this subgroup. Similarly, the trend toward an increased risk of reoperation for open fractures (23%) was not seen until 62 patients with open fractures were enrolled.

Conclusions: Our findings highlight the risk of conducting a trial with insufficient sample size and power. Such studies are not only at risk of missing true effects but also of giving misleading results.

PubMed Disclaimer

Figures

Figure 1
Figure 1
shows the overall SPRINT results by sample size
Figure 2
Figure 2
shows the SPRINT results by sample size for closed fractures.
Figure 3
Figure 3
shows the SPRINT results by sample size for open fractures
See this image and copyright information in PMC

Comment in

  • (Effect) size matters!
    Ebramzadeh E. Ebramzadeh E. J Orthop Trauma. 2013 Apr;27(4):188-9. doi: 10.1097/BOT.0b013e31826ba296. J Orthop Trauma. 2013. PMID: 22874116 No abstract available.

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Lochner HV, Bhandari M, Tornetta P., III Type-II error rates (beta errors) of randomized trials in orthopaedic trauma. J Bone Joint Surg Am. 2001;83:1650–5. - PubMed
    1. Bhandari M, Guyatt G, Tornetta P, 3rd, et al. SPRINT Investigators. Study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures (S.P.R.I.N.T.): study rationale and design. BMC Musculoskeletal Disord. 2008;9:91–105. - PMC - PubMed
    1. Bhandari M, Guyatt G, Tornetta P, III, et al. SPRINT Investigators. . Randomized Trial of Reamed and Unreamed Intramedullary Nailing of Tibial Shaft Fractures. J Bone Joint Surg Am. 2008;90:2567–78. - PMC - PubMed
    1. Chow SC, Shao J, Wang H. Sample Size Calculations in Clinical Research. Marcel Dekker Inc; New York: 2003. Large sample tests for proportions; pp. 81–113.
    1. SPRINT Investigators. Study to prospectively evaluate reamed intramedullary nails in patients with tibial fractures (S.P.R.I.N.T). Study rationale and design. BMC. 2008;9:91. - PMC - PubMed

Publication types