Q J Med 2015; 108:387–396 doi:10.1093/qjmed/hcu217 Advance Access Publication 21 October 2014
Chronic disabling disease—impact on outcomes and costs in emergency medical admissions S. COURNANE1, D. BYRNE2, D. O’RIORDAN2, B. FITZGERALD3 and B. SILKE2 From the 1Medical Physics and Bioengineering Department, 2Division of Internal Medicine and 3 Office of the CEO, St. James’s Hospital, Dublin 8, Ireland Address correspondence to S. Cournane, Medical Physics and Bioengineering Department, St James’s Hospital, Dublin 8, Ireland. email: [email protected] Received 14 August 2014 and in revised form 7 October 2014
Summary Background: Chronic disabling disease is present in nearly 90% of emergency medical admissions. We have examined its impact on outcomes and costs in one institution, using a database of episodes collected prospectively over 12 years. Methods: All emergency admissions (66 933 episodes; 36 271 patients) to St James’ Hospital over a 12-year period (2002–13) were evaluated in relation to 30-day in-hospital mortality, length of stay (LOS) and hospital costs. Predictor variables (identified univariately) were entered into a multi-variable logistic regression model to predict 30-day in-hospital mortality. The data were also modelled as count data (absolute LOS, total cost) using zero-truncated Poisson regression. Results: Acute illness severity was the best independent predictor of mortality; chronic disabling disease was an independent predictor (P < 0.001) for patients with 4+ disabling conditions.
Age, adjusted for other predictors, was only independently predictive of mortality for patient 85+ years. Chronic disabling disease was an independent predictor of LOS increasing linearly with incidence rate ratios of 1.35 (95% CI: 1.29, 1.42), 1.59 (95% CI: 1.51, 1.66), 1.73 (95% CI: 1.65, 1.83) and 1.74 (95% CI: 1.65, 1.84) for those with 1, 2, 3 or 4+ disabling conditions, respectively. Age, as a predictor of LOS was strongly correlated with the presence of disabling disease. Chronic disabling disease independently predicted costs non-linearly; those with 2 or more disabling conditions had particularly high total hospital costs. Conclusion: Chronic disabling disease is an independent predictor of hospital LOS and costs in unselected emergency admissions; adjusted for illness severity, it is only a mortality predictor for those with multiple disabling conditions.
Introduction
disabling disease or disability broadly refers to an impairment of an individual’s ability to function during routine daily tasks, for example cardiac failure or respiratory impairment. Therefore, although quantity of life has increased owing to improved living standards, prevention programmes and medical innovation, full quality of life during these extended years cannot be assumed.3 We recently described a chronic disability score, derived from counts of discharge International Classification of Diseases, Ninth Revision ICD9/ ICD10 codes, that strongly correlated with mortality
Health trends suggest that while life expectancy has increased by 4.0 and 2.6 years for males and females, respectively, over the last four decades (1970–2010) the time spent with a diagnosed chronic ‘disabling’ condition has increased by 9.2 and 9.4 years for males and females, respectively, over the same time period.1 These findings were based on an operational definition of a ‘chronic disabling condition’ as proposed by the US Department of Health and Human Services.2 In this context,
! The Author 2014. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved. For Permissions, please email: [email protected]
388
S. Cournane et al.
and length of stay (LOS).4 Between 2002 and 2013 with 66 933 episodes in patients admitted as a medical emergency, who completed the hospital episode or suffered an in-hospital death by Day 30, only 11.3% of such episodes had no disabling disease code. The episode frequency of 1, 2, 3 or 4+ disabling codes was 24.7%, 29.2%, 21.0% and 13.8%, respectively; clearly with such occurrence there is every justification for focusing on these diagnoses as drivers of healthcare costs and factors in resource utilization. Chronic disabling disease can be expected to be a driver for demand in healthcare services; there is of course increasing emphasis to identify service effectiveness5,6 and achieve greater healthcare cost-efficiency.7 In our previous article, we were of the view that chronic disabling disease would be strongly associated with age and costs. The purpose of this work was to examine the presence of chronic disabling disease, from a database of unselected emergency medical patients admitted over a 12-year period, in terms of outcomes (30-day in-hospital mortality and LOS) and hospital total costs, when adjusted for other predictor variables, including acute illness severity, age groupings and other comorbidities.
Methods Background St James’s Hospital (SJH) serves as a secondary care centre for emergency admissions from its local Dublin catchment area of 270 000 adults. All emergency medical admissions are referred to one of nine teams operating a 1:9 24-hr on-call roster. The ‘on-call’ system is covered by a ‘physician of the day’ with a post-call review round. Emergency medical patients are admitted from the Emergency Department to an Acute Medical Assessment Unit (AMAU) opened in 2003, the operation and outcome of which have been described elsewhere.8,9
Data collection We employed an anonymous patient database assembling core information about each clinical episode from elements contained on the patient administration system, the national hospital in-patient enquiry (HIPE) scheme, the patient electronic record, the emergency room and laboratory systems. HIPE is a national database of coded discharge summaries from acute public hospitals in Ireland.10,11 Ireland used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for both diagnosis and procedure
coding from 1990 to 2005 and ICD-10-CM since then. Data held on the database include the unique hospital number, admitting consultant, date of birth, gender, area of residence, principal and up to nine additional secondary diagnoses and procedures, and admission and discharge dates. Additional information cross-linked and automatically uploaded to the database includes physiological, haematological and biochemical parameters. Data were related to all emergency general medical patients admitted to SJH in the 12 years between 2002 and 2013. Approximately 9.9% of our patients stay >30 days with a median LOS of 54.8 days (interquartile ranges (IQR) 38.8, 97.2). Consequently, the LOS data represent a highly skewed distribution. Although the clinical episode is complete for the majority by Day 30, some patients remain for social reasons related to the lack of long-term care facilities. We have therefore chosen a truncated endpoint (at the 30-day endpoint) for analysis to avoid these additional confounders.
Disability and disabling scores Discharge codes were interrogated to construct a ‘disabling score’. To devise the score, we searched ICD9 codes (back-mapping ICD10 codes to ICD9 as appropriate as Stata routines support ICD9 and not ICD10 ‘calls’) matching ‘chronic disabling’ codes based on the definition proposed by the US Department of Health and Human Services for a ‘chronic disabling condition’.2 The codes were grouped by system, as presented in Table 1. This code search was refined by supplementation from additional hospital databases and available clinical measurements. For instance, the hospital ‘Diamond’ database matched known diabetics (included in Group 5), admission modification of diet in renal disease (MDRD) values (using the extended equation (MDRD value = 170 Serum Creatinine0.999 Age0.176 [0.742 if female] [1.210 if Black] BUN0.176 Albumin+0.318) < 60 ml/min/m2 as evidence of chronic renal insufficiency (included in Group 6)12,13 and an FEV1/FVC ratio
Chronic disabling disease—impact on outcomes and costs in emergency medical admissions S. COURNANE1, D. BYRNE2, D. O’RIORDAN2, B. FITZGERALD3 and B. SILKE2 From the 1Medical Physics and Bioengineering Department, 2Division of Internal Medicine and 3 Office of the CEO, St. James’s Hospital, Dublin 8, Ireland Address correspondence to S. Cournane, Medical Physics and Bioengineering Department, St James’s Hospital, Dublin 8, Ireland. email: [email protected] Received 14 August 2014 and in revised form 7 October 2014
Summary Background: Chronic disabling disease is present in nearly 90% of emergency medical admissions. We have examined its impact on outcomes and costs in one institution, using a database of episodes collected prospectively over 12 years. Methods: All emergency admissions (66 933 episodes; 36 271 patients) to St James’ Hospital over a 12-year period (2002–13) were evaluated in relation to 30-day in-hospital mortality, length of stay (LOS) and hospital costs. Predictor variables (identified univariately) were entered into a multi-variable logistic regression model to predict 30-day in-hospital mortality. The data were also modelled as count data (absolute LOS, total cost) using zero-truncated Poisson regression. Results: Acute illness severity was the best independent predictor of mortality; chronic disabling disease was an independent predictor (P < 0.001) for patients with 4+ disabling conditions.
Age, adjusted for other predictors, was only independently predictive of mortality for patient 85+ years. Chronic disabling disease was an independent predictor of LOS increasing linearly with incidence rate ratios of 1.35 (95% CI: 1.29, 1.42), 1.59 (95% CI: 1.51, 1.66), 1.73 (95% CI: 1.65, 1.83) and 1.74 (95% CI: 1.65, 1.84) for those with 1, 2, 3 or 4+ disabling conditions, respectively. Age, as a predictor of LOS was strongly correlated with the presence of disabling disease. Chronic disabling disease independently predicted costs non-linearly; those with 2 or more disabling conditions had particularly high total hospital costs. Conclusion: Chronic disabling disease is an independent predictor of hospital LOS and costs in unselected emergency admissions; adjusted for illness severity, it is only a mortality predictor for those with multiple disabling conditions.
Introduction
disabling disease or disability broadly refers to an impairment of an individual’s ability to function during routine daily tasks, for example cardiac failure or respiratory impairment. Therefore, although quantity of life has increased owing to improved living standards, prevention programmes and medical innovation, full quality of life during these extended years cannot be assumed.3 We recently described a chronic disability score, derived from counts of discharge International Classification of Diseases, Ninth Revision ICD9/ ICD10 codes, that strongly correlated with mortality
Health trends suggest that while life expectancy has increased by 4.0 and 2.6 years for males and females, respectively, over the last four decades (1970–2010) the time spent with a diagnosed chronic ‘disabling’ condition has increased by 9.2 and 9.4 years for males and females, respectively, over the same time period.1 These findings were based on an operational definition of a ‘chronic disabling condition’ as proposed by the US Department of Health and Human Services.2 In this context,
! The Author 2014. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved. For Permissions, please email: [email protected]
388
S. Cournane et al.
and length of stay (LOS).4 Between 2002 and 2013 with 66 933 episodes in patients admitted as a medical emergency, who completed the hospital episode or suffered an in-hospital death by Day 30, only 11.3% of such episodes had no disabling disease code. The episode frequency of 1, 2, 3 or 4+ disabling codes was 24.7%, 29.2%, 21.0% and 13.8%, respectively; clearly with such occurrence there is every justification for focusing on these diagnoses as drivers of healthcare costs and factors in resource utilization. Chronic disabling disease can be expected to be a driver for demand in healthcare services; there is of course increasing emphasis to identify service effectiveness5,6 and achieve greater healthcare cost-efficiency.7 In our previous article, we were of the view that chronic disabling disease would be strongly associated with age and costs. The purpose of this work was to examine the presence of chronic disabling disease, from a database of unselected emergency medical patients admitted over a 12-year period, in terms of outcomes (30-day in-hospital mortality and LOS) and hospital total costs, when adjusted for other predictor variables, including acute illness severity, age groupings and other comorbidities.
Methods Background St James’s Hospital (SJH) serves as a secondary care centre for emergency admissions from its local Dublin catchment area of 270 000 adults. All emergency medical admissions are referred to one of nine teams operating a 1:9 24-hr on-call roster. The ‘on-call’ system is covered by a ‘physician of the day’ with a post-call review round. Emergency medical patients are admitted from the Emergency Department to an Acute Medical Assessment Unit (AMAU) opened in 2003, the operation and outcome of which have been described elsewhere.8,9
Data collection We employed an anonymous patient database assembling core information about each clinical episode from elements contained on the patient administration system, the national hospital in-patient enquiry (HIPE) scheme, the patient electronic record, the emergency room and laboratory systems. HIPE is a national database of coded discharge summaries from acute public hospitals in Ireland.10,11 Ireland used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for both diagnosis and procedure
coding from 1990 to 2005 and ICD-10-CM since then. Data held on the database include the unique hospital number, admitting consultant, date of birth, gender, area of residence, principal and up to nine additional secondary diagnoses and procedures, and admission and discharge dates. Additional information cross-linked and automatically uploaded to the database includes physiological, haematological and biochemical parameters. Data were related to all emergency general medical patients admitted to SJH in the 12 years between 2002 and 2013. Approximately 9.9% of our patients stay >30 days with a median LOS of 54.8 days (interquartile ranges (IQR) 38.8, 97.2). Consequently, the LOS data represent a highly skewed distribution. Although the clinical episode is complete for the majority by Day 30, some patients remain for social reasons related to the lack of long-term care facilities. We have therefore chosen a truncated endpoint (at the 30-day endpoint) for analysis to avoid these additional confounders.
Disability and disabling scores Discharge codes were interrogated to construct a ‘disabling score’. To devise the score, we searched ICD9 codes (back-mapping ICD10 codes to ICD9 as appropriate as Stata routines support ICD9 and not ICD10 ‘calls’) matching ‘chronic disabling’ codes based on the definition proposed by the US Department of Health and Human Services for a ‘chronic disabling condition’.2 The codes were grouped by system, as presented in Table 1. This code search was refined by supplementation from additional hospital databases and available clinical measurements. For instance, the hospital ‘Diamond’ database matched known diabetics (included in Group 5), admission modification of diet in renal disease (MDRD) values (using the extended equation (MDRD value = 170 Serum Creatinine0.999 Age0.176 [0.742 if female] [1.210 if Black] BUN0.176 Albumin+0.318) < 60 ml/min/m2 as evidence of chronic renal insufficiency (included in Group 6)12,13 and an FEV1/FVC ratio
