Clinical Epidemiology (Apr 2022)

Development and Validation of a Nordic Multimorbidity Index Based on Hospital Diagnoses and Filled Prescriptions

  • Kristensen KB,
  • Lund LC,
  • Jensen PB,
  • Broe A,
  • Rotbain E,
  • Damkier P,
  • Pottegård A,
  • Andersen JH,
  • Højlund M,
  • Olesen M,
  • Rasmussen L,
  • Hansen MR,
  • Ernst MT,
  • Wesselhoeft R,
  • Henriksen DP,
  • Reilev M,
  • Bliddal M,
  • Hallas J

Journal volume & issue
Vol. Volume 14
pp. 567 – 579

Abstract

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Kasper Bruun Kristensen,1 Lars Christian Lund,1 Peter Bjødstrup Jensen,1 Anne Broe,1 Emelie Rotbain,2 Per Damkier,1,3,4 Anton Pottegård,1 Jacob Harbo Andersen,1 Mikkel Højlund,1,5 Morten Olesen,1 Lotte Rasmussen,1 Morten Rix Hansen,1,3,4 Martin Thomsen Ernst,1 Rikke Wesselhoeft,1,6 Daniel Pilsgaard Henriksen,3 Mette Reilev,1 Mette Bliddal,1,7 Jesper Hallas1 1Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, Odense, Denmark; 2Department of Hematology, Odense University Hospital, Odense, Denmark; 3Department of Clinical Pharmacology, Odense University Hospital, Odense, Denmark; 4Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 5Department of Psychiatry Aabenraa, Mental Health Services in the Region of Southern Denmark, Aabenraa, Denmark; 6Child and Adolescent Psychiatry Odense, Mental Health Services in the Region of Southern Denmark, Odense, Denmark; 7Research Unit OPEN, Department of Clinical Research, University of Southern Denmark, Odense, DenmarkCorrespondence: Jesper Hallas, Clinical Pharmacology, Pharmacy and Environmental Medicine, Department of Public Health, University of Southern Denmark, J.B. Winsløws Vej 19, 2, Odense, 5000, Denmark, Tel +4565503010, Email [email protected]: To develop the Nordic Multimorbidity Index (NMI), a multimorbidity measure specifically suited to the Nordic health and administrative registry data based on current diagnosis, treatment, and coding practices.Methods: The NMI was developed to predict 5-year mortality in a population-based cohort of randomly sampled Danish residents aged ≥ 40 years (n = 425,087) followed from 2013 to 2018. Included predictors were selected from hospital diagnoses and filled drug prescriptions based on a combination of subject matter knowledge and a data-driven approach using backwards elimination. The performance of the NMI was assessed in a temporal validation cohort of Danish residents followed from 2007 to 2012 and in six cohorts of new users of selected drugs. The discriminative performance of the NMI, Charlson Comorbidity Index (CCI) and the Elixhauser Comorbidity Index (ECI) was assessed using the c-statistic from logistic regression models with 5-year mortality as dependent variable and the multimorbidity index score, age, and sex as independent variables.Results: The NMI included 50 predictors. In the temporal validation cohort, the c-statistic of the NMI (0.887, 95% CI 0.883– 0.890) exceeded that of the CCI (0.871, 95% CI 0.868– 0.874) and ECI (0.866, 95% CI 0.863– 0.870). In all new user cohorts, the NMI outperformed the other indices with c-statistics ranging from 0.781 (95% CI 0.779– 0.784) to 0.838 (95% CI 0.834– 0.842).Conclusion: The NMI predicted 5-year mortality in a general Danish population and six cohorts of new users of selected drugs and was superior to the CCI and ECI. The NMI could be preferred over these indices to quantify the level of multimorbidity for, eg, descriptive purposes or confounding control. The NMI should be validated in other patient populations and other Nordic countries.Keywords: multimorbidity, comorbidity, pharmacoepidemiology, prognosis, risk score

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