How much does hyperkalemia lengthen inpatient stays? About methodological issues in analyzing time-dependant events

Adverse events may increase the hospital length of stay (LOS). As a consequence, computing the mean difference of LOS between two inpatient groups, with or without event, is a convenient way to evaluate their severity. Conversely, some adverse events are time-dependent: this leads to overestimate the consequences of the adverse event when statistical tests are performed. In this paper, we interest on hyperkalemia in the inpatient database of a community hospital (2% of the inpatient stays). The cumulated risk of hyperkalemia appears to be a linear function of the LOS. We compute the LOS difference associated with hyperkalemia by using 17 statistical methods. The raw LOS difference is 8.8 days, but the simulation finds a difference of 2.3 days, while the regressions (with linear or log link, with or without pairing, with or without propensity score) find a difference of 4.4 to 4.6 days. The characteristics of the methods are discussed, but it is not possible to know which one is true. However the raw difference seems to overestimate the truth. This methodological bias is quite frequent and is a challenge in public health, as it participates in false knowledge discovery, which could lead decision makers to focus on wrong issues and make wrong decisions.

[1]  K. Hauck,et al.  How Dangerous is a Day in Hospital?: A Model of Adverse Events and Length of Stay for Medical Inpatients , 2011, Medical care.

[2]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[3]  D. Classen,et al.  Adverse drug events in hospitalized patients. Excess length of stay, extra costs, and attributable mortality. , 1997, JAMA.

[4]  P. Maurette.  [To err is human: building a safer health system]. , 2002, Annales francaises d'anesthesie et de reanimation.

[5]  David W. Bates,et al.  Incidence of Adverse Drug Events and Medication Errors in Japan: the JADE Study , 2010, Journal of General Internal Medicine.

[6]  P. Palevsky,et al.  Hyperkalemia in hospitalized patients: causes, adequacy of treatment, and results of an attempt to improve physician compliance with published therapy guidelines. , 1998, Archives of internal medicine.

[7]  Marlene R. Miller,et al.  Excess length of stay, charges, and mortality attributable to medical injuries during hospitalization. , 2003, JAMA.

[8]  B. Montague,et al.  Retrospective review of the frequency of ECG changes in hyperkalemia. , 2008, Clinical journal of the American Society of Nephrology : CJASN.

[9]  Katherine E Henson,et al.  Risk of Suicide After Cancer Diagnosis in England , 2018, JAMA psychiatry.

[10]  S. Boorjian,et al.  The implications of hospital acquired adverse events on mortality, length of stay and costs for patients undergoing radical cystectomy for bladder cancer. , 2012, The Journal of urology.

[11]  M. Buckley,et al.  Electrolyte disturbances associated with commonly prescribed medications in the intensive care unit , 2010, Critical care medicine.

[12]  A. Wall,et al.  Book ReviewTo Err is Human: building a safer health system Kohn L T Corrigan J M Donaldson M S Washington DC USA: Institute of Medicine/National Academy Press ISBN 0 309 06837 1 $34.95 , 2000 .

[13]  D. Bates,et al.  Patient risk factors for adverse drug events in hospitalized patients. ADE Prevention Study Group. , 1999, Archives of internal medicine.

[14]  S D Small,et al.  The costs of adverse drug events in hospitalized patients. Adverse Drug Events Prevention Study Group. , 1998, JAMA.

[15]  L. Kohn,et al.  To Err Is Human : Building a Safer Health System , 2007 .

[16]  D. Bates,et al.  The Costs of Adverse Drug Events in Hospitalized Patients , 1997 .