TY - JOUR
T1 - Using datasets to ascertain the generalizability of clinical cohorts
T2 - The example of the European QUALity study on the treatment of advanced chronic kidney disease
AU - EQUAL Study Investigators
AU - Rao, Anirudh
AU - MacNeill, Stephanie J
AU - van de Luijtgaarden, Moniek W M
AU - Chesnaye, Nicholas C
AU - Drechsler, Christiane
AU - Wanner, Chistoph
AU - Torino, Claudia
AU - Postorino, Maurizio
AU - Szymczak, Maciej
AU - Evans, Marie
AU - Dekker, Friedo W
AU - Jager, Kitty J
AU - Ben-Shlomo, Yoav
AU - Caskey, Fergus J
N1 - Publisher Copyright: © 2021 The Author(s). Published by Oxford University Press on behalf of the ERA.
PY - 2022/3/1
Y1 - 2022/3/1
N2 - Background: Cohort studies are among the most robust of observational studies but have issues with external validity. This study assesses threats to external validity (generalizability) in the European QUALity (EQUAL) study, a cohort study of people >65 years of age with Stage 4/5 chronic kidney disease. Methods: Patients meeting the EQUAL inclusion criteria were identified in The Health Improvement Network database and stratified into those attending renal units, a secondary care cohort (SCC) and a not primary care cohort (PCC). Survival, progression to renal replacement therapy (RRT) and hospitalization were compared. Results: The analysis included 250, 633 and 2464 patients in EQUAL, PCC and SCC. EQUAL had a higher proportion of men compared with PCC and SCC (60.0% versus 34.8% versus 51.4%). Increasing age ≥85 years {odds ratio [OR] 0.25 [95% confidence interval (CI) 0.15-0.40]} and comorbidity [Charlson Comorbidity Index ≥4, OR 0.69 (95% CI 0.52-0.91)] were associated with non-participation in EQUAL. EQUAL had a higher proportion of patients starting RRT at 1 year compared with SCC (8.1% versus 2.1%; P < 0.001). Patients in the PCC and SCC had increased risk of hospitalization [incidence rate ratio 1.76 (95% CI 1.27-2.47) and 2.13 (95% CI 1.59-2.86)] and mortality at 1 year [hazard ratio 3.48 (95% CI 2.1-5.7) and 1.7 (95% CI 1.1-2.7)] compared with EQUAL. Conclusions: This study provides evidence of how participants in a cohort study can differ from the broader population of patients, which is essential when considering external validity and application to local practice.
AB - Background: Cohort studies are among the most robust of observational studies but have issues with external validity. This study assesses threats to external validity (generalizability) in the European QUALity (EQUAL) study, a cohort study of people >65 years of age with Stage 4/5 chronic kidney disease. Methods: Patients meeting the EQUAL inclusion criteria were identified in The Health Improvement Network database and stratified into those attending renal units, a secondary care cohort (SCC) and a not primary care cohort (PCC). Survival, progression to renal replacement therapy (RRT) and hospitalization were compared. Results: The analysis included 250, 633 and 2464 patients in EQUAL, PCC and SCC. EQUAL had a higher proportion of men compared with PCC and SCC (60.0% versus 34.8% versus 51.4%). Increasing age ≥85 years {odds ratio [OR] 0.25 [95% confidence interval (CI) 0.15-0.40]} and comorbidity [Charlson Comorbidity Index ≥4, OR 0.69 (95% CI 0.52-0.91)] were associated with non-participation in EQUAL. EQUAL had a higher proportion of patients starting RRT at 1 year compared with SCC (8.1% versus 2.1%; P < 0.001). Patients in the PCC and SCC had increased risk of hospitalization [incidence rate ratio 1.76 (95% CI 1.27-2.47) and 2.13 (95% CI 1.59-2.86)] and mortality at 1 year [hazard ratio 3.48 (95% CI 2.1-5.7) and 1.7 (95% CI 1.1-2.7)] compared with EQUAL. Conclusions: This study provides evidence of how participants in a cohort study can differ from the broader population of patients, which is essential when considering external validity and application to local practice.
KW - Cohort study
KW - EQUAL
KW - External validity
KW - Generalizability
KW - THIN
UR - http://www.scopus.com/inward/record.url?scp=85119435325&partnerID=8YFLogxK
U2 - https://doi.org/10.1093/ndt/gfab002
DO - https://doi.org/10.1093/ndt/gfab002
M3 - Article
C2 - 33426560
SN - 0931-0509
VL - 37
SP - 540
EP - 547
JO - Nephrology, dialysis, transplantation
JF - Nephrology, dialysis, transplantation
IS - 3
ER -