Predictors of 30-Day Readmissions for Adrenal Insufficiency

In This Article

Abstract and Introduction

Abstract

Objective: The aim of this study was to describe rates and characteristics of non-elective 30-day readmission among patients hospitalized for adrenal insufficiency and to assess predictors of readmission.

Design: We analysed the 2018 National Readmission Database. Adrenal insufficiency hospitalizations were identified using the International Classification of Diseases, Tenth Revisions, Clinical Modification diagnosis codes for principal diagnostic codes of primary adrenal insufficiency, Addisonian crisis, drug-induced adrenocortical insufficiency, and other and unspecified adrenocortical insufficiency.

Patients During the study period, 7738 index hospitalizations were identified as patients with AI who met the inclusion criteria. Of these, 7691 were discharged alive.

Measurements: We utilized chi-squared tests to compare baseline characteristics between readmissions and index hospitalizations. Multivariate Cox regression was used to identify independent predictors of readmission.

Results: The 30-day all-cause readmission rate for AI was 17.3%. About 1 in 5 readmissions was for AI. Other reasons for readmission included sepsis (10.8%), unspecified pneumonia (3.1%) and acute renal failure unspecified (1.6%). Readmission was associated with significantly higher odds of inpatient mortality. Independent predictors of 30-day all-cause readmissions included index hospitalizations with the Charlson Comorbidity Index (CCI) ≥3 (adjusted hazards ratio (aHR): 2.53, 95% CI: 1.85–3.46, p < .001), protein-energy malnutrition (aHR: 1.28, 95% CI: 1.02–1.60, p = .035) and obesity (aHR: 1.26, 95% CI: 1.02–1.56, p = .035).

Conclusions: The 30-day all-cause readmission rate was 17.3%. AI was the most common reason for readmission among other causes. Readmissions were associated with increased mortality. CCIs of 3 or more, protein-energy malnutrition and obesity were significant predictors of readmission.

Introduction

Adrenal insufficiency (AI) is defined as the clinical manifestation of absence or deficiency in the production of glucocorticoids.^[1] AI can be further classified as either primary or central insufficiency.^[2,3] Primary AI is characterized by deficient steroid production in the adrenal cortex, whereas central AI is deficiency secondary to disorders in the hypothalamic-pituitary-adrenal (HPA) axis.^[2] Clinically, it is characterized by several cardinal symptoms including anorexia, orthostatic hypotension, salt craving, weakness, fatigue and hyperpigmentation of the skin specifically in primary adrenal insufficiency.^[1] If left untreated, most patients with adrenal insufficiency die within 2 years of their diagnosis, underscoring the potential deadliness of AI.^[4] Moreover, recent studies have reported increases in standardized mortality in primary AI patients and a reduced life expectancy of up to 11 years, which has been largely attributed to infection and cardiovascular diseases in patients with AI.^[4]

Because of its relative rarity, AI hospitalizations have been difficult to study.^[4] Previous research has examined patient characteristics, comorbidities and hospitalizations in AI patients. One cohort database study found that patients with AI had higher rates of comorbidities and inpatient admissions than matched 1:1 controls, which were selected from the general population in the same insurance database using the greedy algorithm based on age, region, gender and insurance type.^[4] Additionally, research has been published about patient-oriented healthcare outcomes in hospitalized patients and found that AI was associated with longer hospital stay, higher rates of ICU admissions and higher rates of hospital readmission.^[5] Despite the known increased rate of readmissions in AI patients, there is a paucity of objective data characterizing readmission hospitalizations, rates of readmission and most importantly the predictors for readmission. This study aimed to contribute to existing literature on AI hospitalizations by evaluating rates of 30-day non-elective readmissions in patients with a diagnosis of AI, differences in readmissions versus index admissions or admissions with a principal diagnosis of AI, and assessing risks of readmission.

Table 1. Top 10 principal diagnoses of readmissions for adrenal insufficiency hospitalizations
Principal readmission diagnosis n = 1352	Proportion, %
Adrenal insufficiency	19.7
Sepsis, unspecified organism	10.8
Unspecified pneumonia	3.1
Unspecified acute renal failure	1.6
Hypertensive heart and CKD with heart failure	1.5
Hypertensive heart disease with heart failure	1.3
Urinary tract infection, unspecified site	1.2
Other pulmonary embolism without acute cor pulmonale	1.1
Type 2 diabetes mellitus with hypoglycaemia without coma	1.1
Chronic obstructive pulmonary disease with (acute) exacerbation	1.1

Table 2. Patient and hospital characteristics of hospitalizations with adrenal insufficiency
Variable	Index admission, %	30-day readmission, %	p value
Variable	n = 7738	n = 1352	p value
Patient characteristics
Age, mean years	58.2 ± 0.7	59.1 ± 1.3	.156
Women	59.4	58.4	.597
Charlson Comorbidity Index score			<.001
0	27.9	15.1
1	20.8	17.5
2	17.4	16.3
≥3	33.9	51.1
Insurance type			<.001
Medicaid	57.3	68.5
Medicare	15.3	16.9
Private	24.4	16.7
Uninsured	3.0	1.9
Median annual income in patient's zip code, US$^#			.135
1–45,999	27.1	30.4
46,000–58,999	28.3	29.2
59,000–78,999	25.1	23.2
≥79,000	19.5	17.2
Comorbidities
Diabetes	29.0	29.0	.998
Hypertension	29.2	25.3	.040
Smoking history	13.3	14.3	.480
CHF	15.5	22.1	<.001
CKD	22.0	26.2	.011
Obesity	15.0	17.6	.060
Dyslipidaemia	31.1	31.5	.850
CAD	18.7	25.2	<.001
Prior CVA	1.9	2.5	.255
Malnutrition	11.8	15.7	.003
COPD	15.5	20.3	<.001
History of neoplasm	18.7	24.4	<.001
Hospital characteristics
Hospital bed size			.557
Small	15.9	14.9
Medium	26.1	24.9
Large	58.0	60.2
Metropolitan location	80.9	79.7	.444
Teaching hospital	72.7	71.0	.333

Abbreviations: CAD, coronary artery disease; CHF, congestive heart failure; CKD, chronic kidney disease; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular accident.
^#For 2018.

Table 3. Clinical outcomes in hospitalizations with adrenal insufficiency
Outcome	Index admission, %	30-day readmission, %	OR (95% CI)	p value*
In-hospital mortality	0.56	4.28	7.88 (4.46–13.93)	<.001*
Length of stay, mean	4.7	5.7	1.0^# (0.6–1.4)	<.001*
Total hospital charges, mean US$	41,477	59,012	17,535^# (11,119–23,952)	<.001*
Total hospital cost, mean US$	10,326	13,814	3488^# (2126–4849)	<.001*

Abbreviations: CI, confidence interval; OR, odds ratio.
*Statistically significant,
^#mean difference.

Table 4. Independent predictors of 30-day all-cause readmissions of adrenal insufficiency hospitalizations
Variable	aHR	95% confidence Interval	p value*
Charlson index of ≥3	2.53	1.85–3.46	<.001*
Against medical advice	1.78	1.09–2.91	.021*
Charlson index of 2	1.54	1.15–2.08	.004*
Protein-energy malnutrition	1.28	1.02–1.60	.035*
Obesity	1.26	1.02–1.56	.035*
History of neoplasm	1.12	0.89–1.40	.325
COPD	1.04	0.86–1.27	.666
Age	0.99	0.996–0.999	.019*
Diabetes	0.94	0.79–1.13	.522
Hypertension	0.86	0.69–1.06	.150
Chronic kidney disease	0.86	0.67–1.09	.204
Private insurance^#	0.64	0.49–0.83	.001*

Abbreviation: aOR, adjusted hazard ratio.
*Statistically significant,
^#relative to Medicaid.

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Predictors of 30-Day Readmissions for Adrenal Insufficiency

A Retrospective National Database Study

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