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Table 1 Sample characteristics, baseline and first waves (no. (%), mean (95% CI))

From: Investigating the causal effect of socioeconomic status on quality of care under a universal health insurance system - a marginal structural model approach

 

Baseline (2000)

First wave (2003)

Low income

High income

P value

Low income

High income

P value

(29–586 USD)

(615–1851 USD)

(26–543 USD)

(543–2594 USD)

N

694,162

2,150,172

 

711,684

2,132,650

 

Place of residence

 Urban

410,251 (59.1%)

1,257,923 (58.5%)

<.001

429,044 (60.3%)

1,274,360 (59.8%)

<.001

 Suburban

239,649 (34.5%)

672,101 (31.3%)

234,431 (32.9%)

632,389 (29.7%)

 Rural

44,262 (6.4%)

220,148 (10.2%)

48,209 (6.8%)

225,901 (10.6%)

Occupation categorya

 1

148,891 (21.4%)

408,848 (19.0%)

<.001

150,682 (21.2%)

385,223 (18.1%)

<.001

 2

260,675 (37.6%)

844,689 (39.3%)

212,327 (29.8%)

853,357 (40.0%)

 3

101 (0.0%)

456,637 (21.2%)

10,839 (1.5%)

446,917 (21.0%)

 4

0 (0.0%)

420,587 (19.6%)

3201 (0.4%)

435,063 (20.4%)

 5

10,542 (1.5%)

884 (0.0%)

14,072 (2.0%)

643 (0.0%)

 6

273,953 (39.5%)

18,527 (0.9%)

320,563 (45.0%)

11,447 (0.5%)

Elixhauser comorbidity index

 0

559,719 (80.6%)

1,755,767 (81.7%)

<.001

547,246 (76.9%)

1,675,097 (78.5%)

0.015

 1–3

129,514 (18.7%)

383,916 (17.9%)

160,105 (22.5%)

450,250 (21.1%)

  ≥ 4

4929 (0.7%)

10,489 (0.5%)

4333 (0.6%)

7303 (0.3%)

 Outpatient visitsb

11.30 (11.27–11.33)

11.52 (11.50–11.53)

<.001

11.41 (11.38–11.43)

11.36 (11.35–11.38)

<.001

 Inpatient Staysb

0.113 (0.112–0.114)

0.095 (0.094–0.095)

<.001

0.120 (0.119–0.121)

0.096 (0.096–0.097)

<.001

 Physician Density of Residenceb

1.573 (1.569–1.577)

1.712 (1.709–1.714)

<.001

1.655 (1.651–1.659)

1.809 (1.806–1.812)

<.001

  1. a Category 1 = civil servants, full-time or regularly paid personnel in governmental agencies and public schools, 2 = employees of privately owned enterprises or institutions, 3 = self-employed, other employees or paid personnel, and members of farmer and fishermen associations, 4 = military personnel, military school students, bereaved families of deceased military personnel, public service in lieu of military service, 5 = low-income citizens, 6 = veterans and dependents, and citizens without a fixed profession from other areas
  2. b Number per 1000 patients