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Table 3 Predictors of log of duration of hospital stay among patients with gout who were admitted to the hospital after presenting to the Emergency Department (ED) with gout using linear regression

From: Gout-related inpatient utilization: a study of predictors of outcomes and time trends

 

Univariate

Multivariable-adjusted

 

B-estimate (95 % CI)

P value

B-estimate (95 % CI)

P value

Age

 <50

Ref

 

Ref

 

 50 to <65

0.12 (0.07, 0.17)

<0.0001

0.07 (0.02, 0.12)

0.0081

 65 to <80

0.20 (0.14, 0.25)

<0.0001

0.07 (0.01, 0.14)

0.0287

 ≥80

0.22 (0.16, 0.27)

<0.0001

0.09 (0.01, 0.17)

0.0234

Gender

 Female

Ref

 

Ref

 

 Male

−0.08 (−0.12, −0.04)

<0.0001

−0.04 (−0.08, 0.00)

0.0518

Median household income

 1st quartile

Ref

 

Ref

 

 2nd quartile

−0.01 (−0.06, 0.03)

0.5966

−0.01 (−0.05, 0.04)

0.7384

 3rd quartile

−0.03 (−0.09, 0.02)

0.2095

−0.03 (−0.08, 0.03)

0.3354

 4th quartile

−0.01 (−0.06, 0.04)

0.6627

−0.02 (−0.07, 0.03)

0.4458

Primary payer

 Medicare

Ref

 

Ref

 

 Medicaid

−0.09 (−0.16, −0.02)

0.0093

−0.05 (−0.12, 0.03)

0.2501

 Private insurance

−0.14 (−0.19, −0.09)

<0.0001

−0.07 (−0.13, −0.01)

0.02

 Self-pay/no charge

−0.25 (−0.31, −0.19)

<0.0001

−0.16 (−0.23, −0.09)

<0.0001

 Other

−0.17 (−0.26, −0.08)

0.0003

−0.08 (−0.18, 0.02)

0.1264

Patient location (residence)

 Micropolitan/not metro

Ref

 

Ref

 

 Metro (large or small)

0.02 (−0.05, 0.08)

0.6063

0.02 (−0.05, 0.09)

0.4927

Hospital region

 Northeast

Ref

 

Ref

 

 Midwest

−0.13 (−0.18, −0.07)

<0.0001

−0.12 (−0.18, −0.07)

<0.0001

 South

−0.03 (−0.09, 0.02)

0.2100

−0.02 (−0.08, 0.03)

0.4363

 West

−0.14 (−0.21, −0.08)

<0.0001

−0.11 (−0.18, −0.04)

0.0025

Teaching status of hospital

 Metropolitan non-teaching or non-metro

Ref

 

Ref

 

 Metropolitan teaching

0.03 (−0.01, 0.07)

0.1344

0.01 (−0.03, 0.06)

0.5442

Comorbidities

 CHD (ref: no)

0.06 (0.02, 0.10)

0.0018

0.01 (−0.04, 0.05)

0.8225

 Hyperlipidemia (ref: no)

−0.00 (−0.04, 0.03)

0.9381

−0.04 (−0.08, 0.01)

0.258

 Renal failure (ref: no)

0.13 (0.09, 0.17)

<0.0001

0.10 (0.06, 0.14)

<0.0001

 Heart failure (ref: no)

0.14 (0.10, 0.17)

<0.0001

0.08 (0.04, 0.12)

0.0002

 Hypertension (ref: no)

0.04 (−0.00, 0.08)

0.0832

−0.04 (−0.08, 0.01)

0.0938

 Diabetes (ref: no)

0.09 (0.05, 0.13)

<0.0001

0.05 (0.01, 0.09)

0.0078

 COPD (ref: no)

0.04 (−0.02, 0.09)

0.2023

−0.02 (−0.08, 0.04)

0.4902

 Osteoarthritis (ref: no)

0.08 (0.03, 0.12)

0.0027

0.06 (0.01, 0.11)

0.0250

  1. Significant beta coefficients are in bold
  2. CI confidence interval, Ref reference category, CHD coronary heart disease, COPD chronic obstructive pulmonary disease
  3. For interpretation in numeric terms for hospital stay, the coefficients from this regression with log (hospital stay) as an outcome should be transformed as ex, where x = beta-estimate. For example, compared to age <50, hospital stay for ages 50 to <65 was 1.07 times higher (beta coefficient = 0.07; e0.07 = 1.07). On the other hand, compared to Medicare, private insurance was associated with 0.93 times (beta coefficient = −0.07; e−0.07 = 0.93) and self-pay/no charge with 0.85 times (beta coefficient = −0.16; e−0.16 = 0.85), the duration of hospital stay. Positive beta-coefficients in this regression with log outcome indicate a longer length of stay and negative beta-coefficients indicate a shorter length of stay. Patients residing in the Midwest had 0.89 times and in the West had 1.57 times the duration of hospital stay (reference, Northeast). Compared to patients without each condition, patients with renal failure had 1.10 times, heart failure, 1.08 times, diabetes, 1.05 times and osteoarthritis, 1.06 times, the duration of hospital stay
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Arthritis Research & Therapy

ISSN: 1478-6362

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