Charlson Comorbidity Index Based On Hospital Episode Statistics Performs Adequately In Predicting Mortality, But Its Discriminative Ability Diminishes Over Time

Figures & data

Figure 1 Kaplan–Meier survival estimates for Deyo’s and Quan’s adaptation of the Charlson Comorbidity Index derived from the hospitalization (HILMO) and medication (SII) data separately and in combination.

Table 1 The Number Of Men By Deyo’s And Quan’s Adaptation Of The Charlson Comorbidity Index (CCI) Based On The Care Registry For Health Care (HILMO) And Medication Data (SII) Separately And In Combination

Comorbidity Score	SII-Based Deyo’s CCI	SII-Based Quan’s CCI	HILMO-Based Deyo’s CCI	HILMO-Based Quan’s CCI	HILMO- And SII-Based Deyo’s CCI	HILMO- And SII-Based Quan’s CCI
0	61,739 (79.7%)	68,381 (88.3%)	68,924 (89.0%)	72,947 (94.2%)	57,891 (74.8%)	65,887 (85.1%)
1	13,250 (17.11%)	7206 (9.3%)	5078 (6.6%)	1443 (1.9%)	13,697 (17.7%)	7225 (9.3%)
2	2107 (2.7%)	1512 (2.0%)	2565 (3.3%)	2570 (3.3%)	4121 (5.3%)	3256 (4.2%)
3+	344 (0.44%)	341 (0.44%)	873 (1.1%)	480 (0.6%)	1731 (2.2%)	1072 (1.4%)

Table 3 Hazard Ratios (HR) Of Death With Their 95% Confidence Intervals (In Parentheses) Of Two Derivations Of The Charlson Comorbidity Index (CCI) Calculated From The Care Registry For Health Care (HILMO), Social Security Institution (SII) And Their Combination

Comorbidity Score	SII-Based Deyo’s CCI	SII-Based Quan’s CCI	HILMO-Based Deyo’s CCI	HILMO-Based Quan’s CCI	HILMO- And SII- Based Deyo’s CCI	HILMO- And SII- Based Quan’s CCI
0	1	1	1	1	1	1
1	1.71 (1.65 −1.76)	1.42 (1.36–1.48)	2.39 (2.29–2.49)	3.24 (3.03–3.47)	1.76 (1.70–1.82)	1.50 (1.44–1.56)
2	2.81 (2.64–2.98)	3.13 (2.93–3.34)	2.96 (2.81–3.13)	3.04 (2.88–3.20)	2.72 (2.59 −2.85)	2.92 (2.78–3.07)
3+	5.21 (4.61–5.88)	4.40 (3.89–4.98)	6.42 (5.95–6.93)	7.03 (6.36–7.77)	5.05 (4.76–5.35)	5.02 (4.68–5.40)

Figure 2 Time-Dependent C-Statistics Calculated Using Age And Combination Of Deyo’s Adaptation Of Charlson Comorbidity Index (CCI) Based On The Care Registry For Health Care (HILMO) And Age As Independent Predictor Variables.

Table 4 Comparison Of Performance And Goodness-Of-Fit Of Two Derivations Of The Charlson Comorbidity Index (CCI) Calculated From The Care Registry For Health Care (HILMO), Social Security Institution (SII) And Their Combination For Predicting Mortality. 95% Confidence Intervals Are Reported In Parentheses When Relevant

Model Covariates	C-Statistic	95% CI	Difference in C-Statistic From Previous Row (or Age*)	Difference in C-Statistic Compared To Age Alone	Difference in C-Statistic Compared To Alternative CCI^a Version	AIC^b
At 1 year
Age	0.622	0.616–0.623				26,370
Age and SII-based Deyo’s CCI	0.676	0.659–0.692	0.0542 (0.0422–0.0662)*	0.0542 (0.0422–0.0662)	0.0151 (0.0080–0.0222)	25,960
Age and HILMO-based Deyo’s CCI	0.722	0.706–0.736	0.0461 (0.0331–0.0591)	0.1003 (0.0862–0.1145)	0.0087 (0.0021–0.0152)	25,469
Age, SII and HILMO-based Deyo ‘s CCI	0.723	0.706–0.739	0.008 (−0.007–0.0086)	0.1011 (0.0858–0.1164)	0.0102 (0.0024–0.0179)	25,541
Age and SII-based Quan’s CCI	0.661	0.644–0.678	0.0392 (0.0290–0.0494)*	0.0392 (0.0290–0.0494)	−0.0151 (−0.0222 – −0.0080)	26,011
Age and HILMO-based Quan’s CCI	0.713	0.697–0.730	0.0525 (0.0404–0.0645)	0.0916 (0.0787–0.1046)	−0.0087 (−0.0152 – −0.0021)	25,470
Age, SII and HILMO-based Quan ‘s CCI	0.713	0.696–0.729	−0.007 (−0.0067–0.0053)	0.0910 (0.0773–0.1046)	−0.0102 (−0.0179 – −0.0024)	25,510
At 5 years
Age	0.620	0.613–0.627				148,402
Age and SII-based Deyo’s CCI	0.654	0.647–0.661	0.0343 (0.300–0.0387)*	0.0343 (0.0300–0.0387)	0.0111 (0.0083–0.0139)	147,277
Age and HILMO-based Deyo’s CCI	0.685	0.678–0.692	0.0305(0.0255–0.0355)	0.0648 (0.5964–0.0700)	0.0105 (0.0076–0.0133)	145,783
Age, SII and HILMO-based Deyo ‘s CCI	0.686	0.680–0.693	0.0017 (−0.0017–0.0049)	0.0664 (0.0608–0.0721)	0.0113 (0.0081–0.0145)	146,761
Age and SII-based Quan’s CCI	0.643	0.636–0.650	0.0232 (0.0198–0.0266)*	0.0232 (0.0198–0.0266)	−0.0111 (−0.0139 – −0.0083)	147,520
Age and HILMO-based Quan’s CCI	0.674	0.667–0.681	0.0311 (0.0267–0.0356)	0.0544 (0.0498–0.0589)	−0.0105 (−0.0133 – −0.0076)	146,095
Age, SII and HILMO-based Quan ‘s CCI	0.675	0.668–0.682	0.0008 (−0.0018–0.0033)	0.0551 (0.0503–0.0600)	−0.0113 (−0.0145 – −0.0081)	146,240
At 13 years
Age	0.619	0.616–0.623				453,143
Age and SII-based Deyo’s CCI	0.644	0.640–0.648	0.0245 (0.0224–0.0267)*	0.0245 (0.0224–0.0267)	0.0105 (0.0090–0.0121)	451,162
Age and HILMO-based Deyo’s CCI	0.656	0.653–0.660	0.0124 (0.0100–0.0149)	0.0370 (0.0346–0.0393)	0.0083 (0.0069–0.0097)	449,559
Age, SII and HILMO-based Deyo ‘s CCI	0.661	0.658–0.665	0.0051 (0.0034–0.0067)	0.0420 (0.0395–0.0446)	0.1185 (0.0103–0.0134)	449,371
Age and SII-based Quan’s CCI	0.633	0.630–0.637	0.0140 (0.0126–0.0154)*	0.0140 (0.0126–0.0154)	−0.0091 (−0.0105 – −0.0076)	451,764
Age and HILMO-based Quan’s CCI	0.648	0.644–0.652	0.0147 (0.0126–0.0167)	0.0287 (0.0266–0.0307)	−0.0083 (−0.0097 –−0.0069)	450,334
Age, SII and HILMO-based Quan ‘s CCI	0.650	0.646–0.653	0.0015 (0.0002–0.0028)	0.0302 (0.0281–0.0323)	−0.1185 (−0.0134 – −0.0103)	450,352

Notes: ^aCharlson’s Comorbidity Index. ^bAIC, Akaike’s Information Criterion; the smaller the AIC value, the better the goodness-of-fit with less information loss. *Difference in C-statistic compared to the model using only age as a covariate.

Table 2 The Survival Rates Of Men At 13 Years By Deyo’s And Quan’s Adaptation Of The Charlson Comorbidity Index (CCI) Based On The Care Registry For Health Care (HILMO) And Medication Data (SII) Separately And In Combination

Comorbidity Score	SII-Based Deyo’s CCI	SII-Based Quan’s CCI	HILMO-Based Deyo’s CCI	HILMO-Based Quan’s CCI	HILMO- And SII- Based Deyo’s CCI	HILMO- And SII- Based Quan’s CCI
0	47,666 (77.2%)	51,534 (75.4%)	53,006 (76.9%)	55,171 (75.6%)	45,659 (78.9%)	50,478 (76.6%)
1	8208 (62.0%)	4715 (65.4%)	2576 (50.7%)	567 (39.3%)	8737 (63.8%)	4743 (65.7%)
2	928 (44.0%)	544 (36.0%)	1125 (43.9%)	1055 (41.1%)	1990 (48.3%)	1382 (42.4%)
3+	76 (22.1%)	85 (24.9%)	171 (19.6%)	85 (17.7%)	492 (28.4%)	275 (25.7%)

Data Availability

The Finnish Prostate Cancer Screening Trial is part of the European Randomised Study of Screening for Prostate Cancer, and the primary data will be released as part of the European trial at their website (www.erspc.org). Preparations for making the data available are in progress. In addition, data from the Finnish and European trial can be requested from the investigators for analysis.