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Missed Readmissions to a Different Hospital in Patients with Peripheral Vascular Disease Associated with Significantly Higher Mortality
Rennier A Martinez, Joshua Parreco, Reagan Lindsay Ross
University of Miami, West Palm Beach, FL

Background
Currently there is a need for accurate nationally representative studies on 30 day readmissions. 30 day readmission rates, which is now a quality outcome measured by CMS, have been previously studied on databases that exclude some payer types, states or certain important data points. Furthermore, current studies do not take into account readmissions that occur a hospital different from index admission. This gap allows for potentially flawed data. The purpose of this study is to examine incidence and risk factors for readmission to a different hospital in patients admitted for claudication or critical limb ischemia. We will look at how this fragmentation of care impacts mortality, amputation rates and overall conclusions regarding currently accepted peripheral vascular disease metrics.
Methods
The 2010-2014 Nationwide Readmissions Database was queried for all patients admitted for claudication or critical limb ischemia whom underwent angioplasty, lower extremity bypass or aorto-bifemoral bypass. Outcomes of interest include: 30 day readmission rates, 30 day readmission rates to another hospital, mortality, and amputation rates. Multivariable logistic regression was used to identify risk factors for readmission to a different hospital. The most common readmission diagnosis was also identified.
Results
92,769 patients were admitted with peripheral vascular disease (33,055 with claudication and 59,714 with CLI). According to Table 1, 30-day readmission/any readmission rate was 8.97%/21.49% and 19.26%/40.36%, for claudication and CLI, respectively. 20.47%/24.92% of 30/365 day readmissions respectively occurred at another hospital. Significantly higher mortality rates were found for patients with 30 day/365 day readmissions to different hospitals with OR 1.4 and 1.8 respectively (Table 2). Multivariable analysis revealed that procedural indication and angioplasty are not a significant risk factor for readmission to a different hospital while female sex, LOS>7 days, hospital teaching status, and Medicaid/Private Insurance remained significant risk factor for this type of readmission. The five most common disease readmission groups found were other vascular procedures (12.6%), amputation of lower limb except toes (6.3%), sepsis (5.4%), heart failure (4.9%) and post op or other device infections (4.8%). Of the above groups the four most common diagnoses included "other post op infections," sepsis, atherosclerosis of native arteries with gangrene, and "other complications due to other vascular device, implant or graft."
Conclusions
Previously unreported, one in four readmissions after lower extremity vascular procedures occur at a different hospital. This fragmentation of care increases mortality rates, and has serious implications for guiding outcome and quality measures. Of equal concern is the fact that we may be using flawed data, given that 25% of patients undergoing lower extremity vascular procedures are being missed by current metrics. Further study into the social and patient specific risk factors may provide a way to prevent these readmissions and improve outcomes in this difficult patient population.

	Table 1. 30/365 Day Readmission to Index and Different Hospital Based on Patient Characteristics
		Total			30 Day RA				30 Day RA to DH%							365 Day RA						365 Day RA to DH%
Characteristic		n	%		n	%			n				%			n			%			n		%
	Total	92769	100		14467	15.5			2961				20.47			31203			33.64			7776		24.92
	Admission Dx
	Claudication	33055	35.6		2966	8.97			610				20.57			7105			21.49			1890		26.60
	CLI	59714	64.4		11501	19.2			2351				20.44			24098			40.36			5886		24.43
	Interventions
	Angioplasty	39997	43.1		6780	16.9			1899				28.01			15088			37.72			4881		32.35
	Peripheral Bypass Graft	45469	49.0		7006	15.4			1304				18.61			14817			32.59			3547		23.94
	Aortofemoral Bypass	5181	5.6		613	11.8			99				16.15			1140			22.00			267		23.42
	Sex
	Female	36992	39.9		6195	16.7			1276				20.60			13053			35.29			3304		25.31
	Male	55268	59.6		8205	14.8			1673				20.39			17993			32.56			4434		24.64
	Age
	>65	57953	62.5		9347	16.1			2000				21.40			20088			34.66			5126		25.52
	<65	34306	37.0		5053	14.7			948				18.76			10958			31.94			2612		23.84
	CCI
	CCI 1-2	46924	51.5		5371	11.4			1006				18.73			12360			26.34			3115		25.20
	CCI 3-5	38535	42.7		7649	19.8			1667				21.79			15956			41.41			3988		24.99
	CCI >5	5190	5.8		1380	26.5			276				20.00			2730			52.60			635		23.26
	LOS
	LOS>7 days	27390	30.8		6636	24.2			1339				20.18			13144			47.99			312		27.44
	LOS<7days	63258	69.2		7764	12.2			1610				20.74			17902			28.30			7426		24.83
	*Results have p values <0.01

Table 2. Univariable and Multivariable Analysis for Mortality
	Univariable					Multivariable
		95% CI					95% CI
Characteristic	OR	Lower	Upper	p		OR	Lower	Upper	p
Admission Dx
Claudication	0.239	0.219	0.26	0.001		0.572	0.331	0.99	0.046
CLI	4.195	3.825	4.6	0.001		1.359	0.781	2.365	0.278
Interventions
Angioplasty	1.601	1.501	1.71	0.001		1.353	1.227	1.493	0.001
Peripheral Bypass Graft	0.712	0.67	0.76	0.001		1.01	0.922	1.106	0.835
Aortofemoral Bypass	0.689	0.591	0.8	0.001		1.359	1.148	1.607	0.001
Sex
Male
Female	1.146	1.078	1.22	0.001		1.065	1.00	1.135	0.052
Age
<65
>65	2.231	2.073	2.4	0.001		2.178	2.02	2.348	0.001
CCI
1-2
3-5	2.289	2.138	2.45	0.001		1.447	1.346	1.556	0.001
>5	4.383	3.964	4.85	0.001		2.228	2.002	2.48	0.001
LOS
LOS<30 days
LOS >30 days	3.993	3.566	4.47	0.001		2.139	1.896	2.414	0.001
LOS<7 days
LOS >7 days	3.118	2.932	3.317	0.001		1.773	1.655	1.899	0.001
Readmission
RA 30 Days	2.655	2.484	2.84	0.001		1.171	1.063	1.291	0.001
RA 30 Day to DH	2.974	2.652	3.34	0.001		1.413	1.171	1.706	0.001
RA 365 days	2.923	2.747	3.109	0.001		1.899	1.742	2.071	0.001
RA 365 days to DH	2.139	1.965	2.33	0.001		0.985	0.86	1.127	0.823

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