Table 2.

Selected matched patient and hospital characteristics

	Before match Focal cases	After match Focal Cases	After match Controls	Before match Controls	Before match	After match
Characteristic (per cent unless noted)	In better nursing resourced hospitals	In better nursing resourced hospitals	In worse nursing resourced hospitals	In worse nursing resourced hospitals	Standardised difference	Standardised difference
	(n=87 847)	(n=62 715)	(n=62 715)	(n=2 12 683)
Age (years), mean	75.7	76.3	76.4	76.8	−0.14	−0.01
Male	41.9	41.2	41.2	41.2	0.01	0.00
Black	4.9	3.9	4.7	3.4	0.08	−0.04
Hispanic	9.2	9.8	8.6	4.6	0.18	0.05
Probability of 30-day mortality	2.7	2.9	2.8	3.2	−0.08	0.01
Emergent admission	24.6	28.0	28.6	34.3	−0.21	−0.01
Transfer-in	0.4	0.5	0.6	0.9	−0.06	−0.02
Comorbidities
Hypertension	83.5	85.0	85.8	87.4	−0.11	−0.02
Diabetes	21.2	22.5	22.4	22.5	−0.03	0.00
Arrhythmia	30.2	29.9	29.7	31.3	−0.02	0.00
COPD	20.2	21.3	21.9	25.6	−0.13	−0.02
Congestive heart failure	15.3	15.7	15.3	16.3	−0.02	0.01
Dementia	11.1	12.6	12.7	13.8	−0.08	0.00
Myocardial infarction	8.9	8.9	9.1	10.3	−0.05	−0.01
Renal failure	5.6	5.7	5.2	5.1	0.02	0.02
Angina	4.3	4.3	4.1	5.8	−0.07	0.01
Hospital characteristics
Small (<250 beds)	22.0	26.6	26.6	40.9	−0.42	0.00
Large (≥250 beds)	78.0	73.4	73.4	59.1	0.42	0.00
Beds, mean	460.4	407.2	381.2	317.3	0.69	0.12
Non-teaching	42.1	57.0	57.0	63.8	−0.45	0.00
Minor teaching	18.2	25.0	25.0	29.5	−0.27	0.00
Major teaching	39.7	17.9	17.9	6.6	0.85	0.00
Resident-to-bed ratio, mean	0.3	0.1	0.1	0.1	0.82	0.08
High technology status	87.7	85.2	85.2	52.3	0.84	0.00

Note: The standardised difference is the difference in means divided by a pooled SD before matching. See online supplementary appendix 1 for a description of the matching algorithm and online supplementary appendix 7 for a complete balance table using all covariates.

COPD, chronic obstructive pulmonary disease.