Comorbidity index in central cancer registries: the value of hospital discharge data

Figures & data

Table 1 Characteristics of cancer cases with comorbidity data in California hospital discharge files

Characteristic	Comorbidity data, %	No comorbidity data, %	Total N
Age at diagnosis (years)
0–19	83.3	16.7	28,360
20–29	71.4	28.6	54,379
30–39	74.6	25.4	131,862
40–49	77.4	22.6	312,023
50–59	79.0	21.0	567,237
60–69	78.2	21.8	807,414
70–79	77.4	22.6	842,901
>80	81.7	18.4	550,410
Sex
Male	75.7	24.3	1,609,739
Female	81.1	18.9	1,684,847
Race/ethnicity
Non-Hispanic White	77.4	22.6	2,296,920
Non-Hispanic Black	79.9	20.1	210,893
Hispanic	82.7	17.3	455,737
Asian/Pacific Islander	83.1	16.9	279,034
Other	80.5	19.5	12,565
Unknown	45.4	54.6	39,437
Year of diagnosis
Years with PDD only (1991–2004)	71.3	28.7	1,846,667
Years with PDD + ASD + EDD (2005–2013)	87.5	12.5	1,447,919
Total	78.4	21.6	3,294,586

Note: Percentages may add up to >100 due to rounding.

Abbreviations: ASD, ambulatory surgery data; EDD, emergency department data; PDD, patient discharge data.

Table 2 Proportion of cancer cases with comorbidity data by cancer type and hospital discharge file

Cancer type	Overall, %	PDD only (1991–2004), %	PDD+ASD+EDD (2005–2013), %	Difference in percent matching by discharge file availability, %a
Corpus uteri	95.9	95.1	96.8	1.8
Gallbladder	95.7	94.8	96.8	1.9
Ovary	95.5	94.7	96.7	1.9
Other digestive organs	95.1	94.0	96.3	2.3
Small intestine	94.9	94.1	95.8	1.6
Stomach	94.1	93.3	95.2	1.9
Kidney and renal pelvis	93.9	93.0	94.7	1.7
Colon	93.1	91.9	95.1	3.3
Pancreas	93.0	91.4	94.8	3.3
Thyroid	92.5	89.9	94.4	4.5
Bones and joints	91.2	89.5	93.5	4.0
Other urinary organs	90.7	86.9	95.7	8.7
Esophagus	89.5	86.2	93.8	7.6
Brain and other nervous system	89.1	89.2	89.0	0.1
Liver and bile duct	89.1	87.6	90.2	2.6
Rectum	88.7	85.5	93.4	7.9
Lung and bronchus	88.4	85.8	92.3	6.5
Uterus, not otherwise specified	86.9	83.2	89.9	6.7
Soft tissue including heart	84.0	76.2	92.9	16.7
Other endocrine	82.3	79.9	83.4	3.5
Other	81.2	78.7	84.4	5.7
Myeloma	77.0	70.9	83.8	12.9
Oral cavity and pharynx	77.0	67.4	89.0	21.6
Urinary bladder	76.6	63.8	93.3	29.5
Breast	75.3	61.3	92.8	31.5
Lymphomas	75.2	65.3	87.6	22.4
Leukemia	74.9	70.9	80.2	9.3
Anus, anal canal, and anorectum	73.5	61.6	82.8	21.2
Other respiratory system	71.4	58.5	92.2	33.7
Testis	71.0	51.9	93.8	41.9
Other female genital organs	69.4	54.7	87.8	33.1
Cervix uteri	67.4	60.8	93.4	32.6
Other male genital organs	64.3	49.9	82.0	32.1
Prostate	62.0	56.4	70.8	14.4
Eye and orbit	59.3	38.2	86.2	47.9
Other nonepithelial skin	58.2	39.5	78.5	39.0
Melanomas – skin	46.7	25.4	66.0	40.7

Note:

a May not be equal to Column 3 (PDD+ASD+EDD) - Column 2 (PDD only) due to rounding.

Abbreviations: ASD, ambulatory surgery data; EDD, emergency department data; PDD, patient discharge data.

Figure 1 Overall survival by comorbidity score for California cancer cases.

Table 3 Association of Charlson Comorbidity Index with overall mortality among California cancer patients

Characteristic		Univariable model			Multivariable model
		HR	95% HR confidence limits		HR	95% HR confidence limits
			Lower	Upper		Lower	Upper
Charlson	0	Reference			Reference
Comorbidity	1	1.99	1.99	2.00	1.50	1.49	1.50
Index Score	2	2.82	2.81	2.84	1.79	1.78	1.80
	3 or higher	3.95	3.93	3.98	2.33	2.32	2.34
Age at diagnosis	Per year				1.04	1.04	1.04
Sex	Male				Reference
	Female				0.85	0.85	0.86
Race/ethnicity	Non-Hispanic White				Reference
	Asian/Pacific Islander				0.85	0.84	0.85
	Hispanic				0.88	0.87	0.88
	Non-Hispanic Black				1.05	1.04	1.05
	Other/unknown				0.64	0.63	0.66
SEER summary stage	In situ				0.69	0.69	0.70
	Localized				Reference
	Regional				1.82	1.81	1.83
	Distant				5.11	5.09	5.13
	Unstaged				3.73	3.71	3.75
SES quintile	1 (lowest SES)				1.39	1.38	1.40
	2				1.29	1.28	1.30
	3				1.21	1.21	1.22
	4				1.12	1.12	1.13
	5 (highest SES)				Reference

Abbreviations: SES, socioeconomic status; HR, hazard ratio; SEER, Surveillance Epidemiology and End Results.

Table 4 Association of hospital discharge- and Medicare-derived Charlson indexes with overall mortality

Comorbidity score	Unadjusted model HR (95% CI)		Adjusted modela HR (95% CI)
	Model using OSHPD-derived score C index = 0.62	Model using SEER-Medicare-derived score C index = 0.59	Model using OSHPD-derived score C index = 0.77	Model using SEER-Medicare-derived score C index = 0.76
1	1.69 (1.67–1.70)	1.45 (1.43–1.46)	1.53 (1.51–1.54)	1.32 (1.31–1.34)
2	2.36 (2.33–2.38)	1.84 (1.82–1.87)	1.91 (1.88–1.93)	1.56 (1.54–1.58)
3 or higher	3.23 (3.19–3.27)	2.51 (2.48–2.53)	2.45 (2.42–2.48)	1.97 (1.95–1.99)

Notes:

a Model adjusted for age, sex, race/ethnicity, cancer stage, and quintile of neighborhood SES.

Abbreviations: HR, hazard ratio; OSHPD, Office of Statewide Health Planning and Development; SES, socioeconomic status; SEER, Surveillance, Epidemiology, and End Results.