Similarities and differences.pdf (948.51 kB)
Similarities and differences between patients included and excluded from a randomized clinical trial of vitamin d supplementation for improving glucose tolerance in prediabetes: interpreting broader applicability.
journal contribution
posted on 2015-11-21, 00:00 authored by Y. Eisenberg, H. Mohiuddin, K. Cherukupally, H. Zaidi, S. Kukreja, E. BarengoltsBackground: Randomized Clinical Trial (RCT) designs range from highly selective resulting in lack of external
validity to more inclusive, requiring large sample sizes to observe significant results. Few publications, however,
have compared excluded to enrolled participants. We aimed to assess our trial’s design based on the effectiveness
versus efficacy continuum using the Pragmatic-Explanatory Continuum Indicator Summary (PRECIS) tool and to
compare included and excluded patients.
Methods: Fifteen members of endocrinology section completed PRECIS for DIVA (D-Vitamin Intervention in VA)
trial; an RCT evaluating vitamin D supplementation in improving dysglycemia in patients with prediabetes.
Retrospective chart review compared subjects excluded (OUT) to those included (IN) in RCT. Student’s t and Chisquare
tests were used to compare continuous and categorical variables. Additionally, multiple logistic regression
was completed.
Results: PRECIS scores were nearly universally pragmatic. 178 patients enrolled in DIVA trial were compared with
178 randomly selected patients excluded from study involvement. There was no significant difference between IN
and OUT for the majority of the continuous and all of the categorical variables. Multivariate logistic regression
identified only the A1c, HDL and Charlson Index as significant predictors of a participant’s inclusion or exclusion.
There was higher HDL (51.3(13.9) versus 44.6(10.1), P = 0.001) and Charlson Index (2.85(1.6) versus 2.2(1.17), P =
0.001) for OUT versus IN groups.
Subanalysis of excluded patients in A1c range 5.7 to 6.9, had lower BMI (30.7(3.4) versus 32(2.7), P = 0.002) but
higher HDL (mg/l: 49.7(11.8) versus 44.6(10.1), P = 0.001) and Charlson index (2.85(1.6) versus 2.2(1.17), P = 0.001)
than included participants. Additionally, there was a trend towards higher rates of cancer (22.9 % versus 12.9 %,
P = 0.033) but less psychiatric problems (56.2 % versus 72.5 %, P = 0.026) and thiazide diuretic use (18.1 % versus
29.8 %, P = 0.034).
Conclusion: DIVA trial design appears to favor broad clinical applicability. The majority of objectively compared
variables did not different between patients included and excluded from this RCT. Advice based on the evidence
from this RCT may be applicable to a larger group of patients than those fitting inclusion/exclusion criteria alone.
Trial registration: ClinicalTrials.gov NCT01375660 (registered 15 June 2011).
Funding
The study was supported by a Merit Review grant funded by the Department of Veterans Affairs, Jesse Brown VA Medical Center and in part by NIH grant number UL1RR029879.
History
Publisher Statement
This is the copy of an article published in Trials © 2015 BioMed Central Publications.Publisher
BioMed Centralissn
1745-6215Issue date
2015-07-15Usage metrics
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