- Email: [email protected]
Comorbidity indices disillusion
Journal of Clinical Epidemiology
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(2015)
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LETTER TO THE EDITOR Comorbidity indices disillusion Recently, some interesting studies about comorbidity appeared on this journal. As geriatricians, we strongly believe that comorbidity is an increasing issue, especially in our field, because aging is connected with a growing incidence of chronic diseases, which become prevalent and synergic in oldest patients [1]. Some agreement emerges from the studies by Boeckxstaens et al. [2], Toson et al. [3], and Yurkovich et al. [4], particularly about the poor value of the more widespread comorbidity tools in predicting adverse clinical events (ACEs) or functional decline after hospitalization. Having been created with calibration on mortality, which is the strongest outcome to use and also the easiest to consider when creating a prognostic score, it is quite predictable that comorbidity indices (e.g., Cumulative Illness Rating Scale [5], Charlson Index [6], and Elixhauser Index [7]) cannot catch other outcomes like ACEs or changes in functional status and quality of life, which are relevant for geriatric population, maybe to the same degree of mortality [8]. An efficient system to evaluate comorbidity to identify patients at high risk of ACEs and poor functional recovery (as intermediate and modifiable outcomes) should be useful especially in postacute care and rehabilitation. To this end in 2012, we developed and validated a score for identifying subjects at increased risk of ACEs, considering 502 patients admitted to postacute care facilities in Lombardia region, Italy. Six variables (age O87 years, delirium, pressure sore, indwelling bladder catheter, malnutrition, and acute infection on admission) were identified as stable predictors of ACEs, but neither comorbidity nor the presence of any particular chronic disease were included in the six variables final score [9]. At the moment, we have available data about more than 600 patients with hip fracture, a population with high prevalence of multimorbidity, admitted to the orthogeriatric unit of our hospital (Istituto Clinico Humanitas, Rozzano-Milano) and surgically treated. Our analysis is still ongoing, but we are oriented to evaluate the performance of some comorbidity indices in relation to major ACEs incidence during hospitalization and to a functional outcome. Preliminary results suggest that comorbidity indices are not suitable for capturing ACEs incidence, as medical instability is not, and not adequate for predicting functional decline as well. Both in daily practice and in preliminary data analysis, we strongly perceive a 0895-4356/Ó 2015 Elsevier Inc. All rights reserved.
substantial uselessness of these comorbidity tools in prognostical terms: they may not be used to guide clinical decision making. It has already been discussed elsewhere that the course of disability at the end of life does not follow a predictable pattern based on the condition leading to death [8]; in other words, functional status and diseases may move on parallel rails, and their causal association is mainly a clinimetric illusion. Comorbidity evaluation indices lack essential information about functional status, so these tools alone are not useful for us to understand the present and the short/medium-term needs of patients. Disease-specific criteria are definitely insufficient to guide clinical practice and management based on patients’ real needs. Bruno Bernardini* Department of Neurorehabilitation Istituto Clinico Humanitas Via Alessandro Manzoni 56, Rozzano 20089, Milan, Italy
Stefania Fracchia Department of Experimental and Clinical Medicine Research Unit of Medicine of Aging University of Florence and Azienda Ospedaliero-Universitaria Careggi Viale Pieraccini, 6 50141 Florence, Italy *Corresponding author. Tel.: þ390282246801; fax: þ390282246891. E-mail address: [email protected] (B. Bernardini)
References [1] Fried LP, Ferrucci L, Darer J, Williamson JD, Anderso G. Untangling the concepts of disability, frailty, and comorbidity: implications for improved targeting and care. J Gerontol 2004;59(3): 255e63. [2] Boeckxstaens P, Vaes B, Van Pottelbergh G, De Sutter A, Legrand D, Adriaensen W, et al. Multimorbidity measures were poor predictors of adverse events in patients aged 80 years: a prospective cohort study. J Clin Epidemiol 2015;68:220e7. [3] Toson B, Harvey LA, Close JCT. The ICD-10 Charlson Comorbidity Index predicted mortality but not resource utilization following hip fracture. J Clin Epidemiol 2015;68:44e51. [4] Yurkovich M, Avina-Zubieta JA, Thomas J, Gorenchtein M, Lacaille D. A systematic review identifies valid comorbidity indices derived from administrative health data. J Clin Epidemiol 2015;68:3e14. [5] Linn BS, Linn MW, Gurel L. Cumulative Illness Rating Scale. J Am Geriatr Soc 1968;16:622e6.
2
Letter to the Editor / Journal of Clinical Epidemiology
[6] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373e83. [7] Elixhauser A, Steiner C, Robert Harris D, Coffey RM. Comorbidity measures for use with administrative data. Med Care 1998;36:8e27. [8] Kurrle S, Cameron ID, Maier AB. Trajectories of disability in the last year of life. N Engl J Med 2010;362:1173e80.
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(2015)
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[9] Bellelli G, Bernardini B, Pievani M, Frisoni GB, Guaita A, Trabucchi M. A score to predict the development of adverse clinical events after transition from acute hospital wards to post-acute care settings. Rejuvenation Res 2012;15(6):553e63.
http://dx.doi.org/10.1016/j.jclinepi.2015.05.014
-
(2015)
-
LETTER TO THE EDITOR Comorbidity indices disillusion Recently, some interesting studies about comorbidity appeared on this journal. As geriatricians, we strongly believe that comorbidity is an increasing issue, especially in our field, because aging is connected with a growing incidence of chronic diseases, which become prevalent and synergic in oldest patients [1]. Some agreement emerges from the studies by Boeckxstaens et al. [2], Toson et al. [3], and Yurkovich et al. [4], particularly about the poor value of the more widespread comorbidity tools in predicting adverse clinical events (ACEs) or functional decline after hospitalization. Having been created with calibration on mortality, which is the strongest outcome to use and also the easiest to consider when creating a prognostic score, it is quite predictable that comorbidity indices (e.g., Cumulative Illness Rating Scale [5], Charlson Index [6], and Elixhauser Index [7]) cannot catch other outcomes like ACEs or changes in functional status and quality of life, which are relevant for geriatric population, maybe to the same degree of mortality [8]. An efficient system to evaluate comorbidity to identify patients at high risk of ACEs and poor functional recovery (as intermediate and modifiable outcomes) should be useful especially in postacute care and rehabilitation. To this end in 2012, we developed and validated a score for identifying subjects at increased risk of ACEs, considering 502 patients admitted to postacute care facilities in Lombardia region, Italy. Six variables (age O87 years, delirium, pressure sore, indwelling bladder catheter, malnutrition, and acute infection on admission) were identified as stable predictors of ACEs, but neither comorbidity nor the presence of any particular chronic disease were included in the six variables final score [9]. At the moment, we have available data about more than 600 patients with hip fracture, a population with high prevalence of multimorbidity, admitted to the orthogeriatric unit of our hospital (Istituto Clinico Humanitas, Rozzano-Milano) and surgically treated. Our analysis is still ongoing, but we are oriented to evaluate the performance of some comorbidity indices in relation to major ACEs incidence during hospitalization and to a functional outcome. Preliminary results suggest that comorbidity indices are not suitable for capturing ACEs incidence, as medical instability is not, and not adequate for predicting functional decline as well. Both in daily practice and in preliminary data analysis, we strongly perceive a 0895-4356/Ó 2015 Elsevier Inc. All rights reserved.
substantial uselessness of these comorbidity tools in prognostical terms: they may not be used to guide clinical decision making. It has already been discussed elsewhere that the course of disability at the end of life does not follow a predictable pattern based on the condition leading to death [8]; in other words, functional status and diseases may move on parallel rails, and their causal association is mainly a clinimetric illusion. Comorbidity evaluation indices lack essential information about functional status, so these tools alone are not useful for us to understand the present and the short/medium-term needs of patients. Disease-specific criteria are definitely insufficient to guide clinical practice and management based on patients’ real needs. Bruno Bernardini* Department of Neurorehabilitation Istituto Clinico Humanitas Via Alessandro Manzoni 56, Rozzano 20089, Milan, Italy
Stefania Fracchia Department of Experimental and Clinical Medicine Research Unit of Medicine of Aging University of Florence and Azienda Ospedaliero-Universitaria Careggi Viale Pieraccini, 6 50141 Florence, Italy *Corresponding author. Tel.: þ390282246801; fax: þ390282246891. E-mail address: [email protected] (B. Bernardini)
References [1] Fried LP, Ferrucci L, Darer J, Williamson JD, Anderso G. Untangling the concepts of disability, frailty, and comorbidity: implications for improved targeting and care. J Gerontol 2004;59(3): 255e63. [2] Boeckxstaens P, Vaes B, Van Pottelbergh G, De Sutter A, Legrand D, Adriaensen W, et al. Multimorbidity measures were poor predictors of adverse events in patients aged 80 years: a prospective cohort study. J Clin Epidemiol 2015;68:220e7. [3] Toson B, Harvey LA, Close JCT. The ICD-10 Charlson Comorbidity Index predicted mortality but not resource utilization following hip fracture. J Clin Epidemiol 2015;68:44e51. [4] Yurkovich M, Avina-Zubieta JA, Thomas J, Gorenchtein M, Lacaille D. A systematic review identifies valid comorbidity indices derived from administrative health data. J Clin Epidemiol 2015;68:3e14. [5] Linn BS, Linn MW, Gurel L. Cumulative Illness Rating Scale. J Am Geriatr Soc 1968;16:622e6.
2
Letter to the Editor / Journal of Clinical Epidemiology
[6] Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis 1987;40:373e83. [7] Elixhauser A, Steiner C, Robert Harris D, Coffey RM. Comorbidity measures for use with administrative data. Med Care 1998;36:8e27. [8] Kurrle S, Cameron ID, Maier AB. Trajectories of disability in the last year of life. N Engl J Med 2010;362:1173e80.
-
(2015)
-
[9] Bellelli G, Bernardini B, Pievani M, Frisoni GB, Guaita A, Trabucchi M. A score to predict the development of adverse clinical events after transition from acute hospital wards to post-acute care settings. Rejuvenation Res 2012;15(6):553e63.
http://dx.doi.org/10.1016/j.jclinepi.2015.05.014