Impact of the Charlson Comorbidity Index score on risk prediction by single-photon emission computed tomography myocardial perfusion imaging following myocardial infarction

Figures & data

Table 1 Patients with normal and abnormal scans by sex, age, comorbidity level, and cardiovascular morbidity

Characteristics	Normal scan (n=362)	Abnormal scan (n=830)	Total (n=1,192)
Sex
Female	165 (46%)	233 (28%)	398 (33%)
Male	197 (54%)	597 (72%)	794 (67%)
Age (years)
18−49	69 (19%)	149 (18%)	218 (18%)
50−59	119 (33%)	236 (28%)	355 (30%)
60−69	95 (26%)	245 (30%)	340 (29%)
≥70	79 (22%)	200 (24%)	279 (23%)
Median age (years)	59	60	60
Comorbidity level*
Low	195 (54%)	369 (44%)	564 (47%)
Moderate	89 (25%)	215 (26%)	304 (26%)
Severe	78 (21%)	246 (30%)	324 (27%)
Cardiovascular morbidity
Congestive heart failure	34 (9%)	171 (21%)	205 (17%)
Peripheral vascular disease	30 (8%)	78 (9%)	108 (9%)
Cerebrovascular disease	30 (8%)	97 (12%)	127 (11%)
Diabetes	43 (12%)	126 (15%)	169 (14%)

Note: Included are patients with a first-time myocardial infarction within 5 years before the scan. *Levels of comorbidity were based on Charlson Comorbidity Index scores as follows: 0 (low), 1 (moderate), and ≥2 (severe).

Table 2 Risk and hazard ratio of MI and all-cause death within 5 years following a normal versus abnormal scan, overall and according to comorbidity level

Outcome	Scan result	No. of events	Risk % (95% CI)	Risk difference % (95% CI)	Hazard ratio (95% CI)
					Unadjusted	Adjusted*
Overall
MI	Normal	41	11.7 (8.5 – 15.5)	6.6 (2.1 – 11.1)	1 (reference)	1 (reference)
		Abnormal	149	18.3 (15.7 – 21.0)	1.64 (1.16 – 2.31)	1.56 (1.09 – 2.21)
All-cause death	Normal	27	8.0 (5.5 – 11.5)	5.2 (1.4 – 8.9)	1 (reference)	1 (reference)
		Abnormal	104	13.2 (11.0 – 15.7)	1.66 (1.09 – 2.54)	1.39 (0.90 – 2.14)
Low comorbidity (0 points)
MI	Normal	24	12.6 (8.1 – 18.1)	4.5 (−1.9 – 10.9)	1 (reference)	1 (reference)
		Abnormal	62	17.1 (13.4 – 21.2)	1.41 (0.88 – 2.25)	1.33 (0.82 – 2.15)
All-cause death	Normal	4	2.1 (0.8 – 5.4)	3.7 (0.5 – 6.8)	1 (reference)	1 (reference)
		Abnormal	20	5.7 (3.7 – 8.8)	2.64 (0.90 – 7.72)	2.33 (0.79 – 6.84)
Moderate comorbidity (1 point)
MI	Normal	10	12.0 (6.1 – 20.0)	4.6 (−4.2 – 13.3)	1 (reference)	1 (reference)
		Abnormal	35	16.5 (11.9 – 21.8)	1.45 (0.72 – 2.93)	1.39 (0.68 – 2.83)
All-cause death	Normal	4	5.2 (2.0 – 13.5)	5.1 (−1.5 – 11.6)	1 (reference)	1 (reference)
		Abnormal	21	10.3 (6.8 – 15.4)	2.04 (0.70 – 5.96)	2.05 (0.69 – 6.06)
Severe comorbidity (≥2 points)
MI	Normal	7	9.0 (4.0 – 16.7)	12.6 (3.8 – 21.4)	1 (reference)	1 (reference)
		Abnormal	52	21.6 (16.7 – 27.1)	2.48 (1.13 – 5.45)	2.53 (1.14 – 5.62)
All-cause death	Normal	19	25.9 (17.3 – 37.7)	0.8 (−10.9 – 12.4)	1 (reference)	1 (reference)
		Abnormal	63	26.6 (21.5 – 32.8)	1.03 (0.62 – 1.72)	1.07 (0.64 – 1.80)

Note: Included are patients with a first-time MI within 5 years before the scan. *Adjusted for sex, age, and comorbidity level in the overall analyses, and sex and age in the analyses stratified on comorbidity level.

Abbreviations: CI, confidence interval; MI, myocardial infarction.

Table 3 30-day, 31−365-day, and 1−5-year risk of MI and all-cause death following a normal versus abnormal scan

Time intervals	Scan result	No. of events	Risk % (95% CI)	Risk difference % (95% CI)
0−30 days
MI	Normal	7	1.7 (0.6 – 3.6)	−0.1 (−1.8 – 1.6)
		Abnormal	14	1.6 (0.9 – 2.6)
All-cause death	Normal	1	0.3 (0.0 – 1.9)	−0.2 (−0.8 – 0.4)
		Abnormal	1	0.1 (0.0 – 0.9)
31−365 days
MI	Normal	15	4.0 (2.2 – 6.5)	3.3 (0.5 – 6.1)
		Abnormal	60	7.2 (5.6 – 9.2)
All-cause death	Normal	6	1.7 (0.8 – 3.7)	0.9 (−0.8 – 2.6)
		Abnormal	21	2.5 (1.7 – 3.9)
1−5 years
MI	Normal	19	6.5 (4.0 – 9.7)	4.1 (0.3 – 7.9)
		Abnormal	75	10.6 (8.4 – 13.0)
All-cause death	Normal	20	6.2 (4.0 – 9.5)	4.6 (1.1 – 8.0)
		Abnormal	82	10.8 (8.8 – 13.2)

Note: Included are patients with a first-time MI within 5 years before the scan.

Abbreviations: CI, confidence interval; MI, myocardial infarction.

Table 4 Risk and hazard ratio of MI registered during an acute admission within 5 years following a normal versus abnormal scan

Outcome	Scan result	No. of events	Risk % (95% CI)	Hazard ratio (95% CI)
				Unadjusted	Adjusted*
MI	Normal	25	7.0 (4.6 – 10.2)	1 (reference)	1 (reference)
	Abnormal	87	10.8 (8.8 – 13.1)	1.54 (0.98 – 2.40)	1.35 (0.86 – 2.12)

Note: Included are patients with a first-time MI within 5 years before the scan. *Adjusted for sex, age, and comorbidity level.

Abbreviations: CI, confidence interval; MI, myocardial infarction.

Table 5 Risk and hazard ratio of MI and all-cause death within 5 years following a normal scan, a reversible defect, a fixed defect, and a combined defect. Included are patients with a first-time MI within 5 years before the scan

Outcome	Scan result	No. of events	Risk % (95% CI)	Hazard ratio (95% CI)
				Unadjusted	Adjusted*
MI	Normal	41	11.7 (8.5 – 15.5)	1 (reference)	1 (reference)
	Reversible defect	21	14.1 (9.1 – 20.2)	1.25 (0.74 – 2.11)	1.22 (0.72 – 2.07)
	Fixed defect	74	18.4 (14.7 – 22.4)	1.67 (1.14 – 2.44)	1.58 (1.07 – 2.33)
	Combined defect	54	20.1 (15.5 – 25.1)	1.81 (1.21 – 2.72)	1.72 (1.14 – 2.61)
All-cause death	Normal	27	8.0 (5.5 – 11.5)	1 (reference)	1 (reference)
	Reversible defect	14	9.7 (5.9 – 15.9)	1.21 (0.64 – 2.31)	0.97 (0.51 – 1.85)
	Fixed defect	49	12.6 (9.7 – 16.3)	1.61 (1.00 – 2.57)	1.41 (0.87 – 2.27)
	Combined defect	41	15.9 (11.9 – 21.0)	2.00 (1.23 – 3.25)	1.61 (0.99 – 2.64)

Note: *Adjusted for sex, age, and comorbidity level.

Abbreviations: CI, confidence interval; MI, myocardial infarction.

Figure 1 Estimated cumulative incidence of all-cause mortality risk among patients with normal and abnormal scans.

Table S1 Diagnosis codes according to the International Classification of Diseases, 8th (ICD-8) and 10th revision (ICD-10)

Disease	Weight	ICD-8 codes	ICD-10 codes
Myocardial infarction	1	410	I21, I22, I23
Congestive heart failure	1	427.09, 427.10, 427.11, 427.19, 428.99, 782.49	I50, I11.0, I13.0, I13.2
Peripheral vascular disease	1	440–445	I70–I74, I77
Cerebrovascular disease	1	430–438	I60–I69, G45, G46
Dementia	1	290.09–290.19, 293.09	F00–F03, F05.1, G30
Chronic pulmonary disease	1	490–493, 515–518	J40–J47, J60–J67, J68.4, J70.1, J70.3, J84.1, J92.0, J96.1, J98.2, J98.3
Connective tissue disease	1	712, 716, 734, 446, 135.99	M05, M06, M08, M09, M30–M36, D86
Ulcer disease	1	530.91, 530.98, 531–534	K22.1, K25–K28
Mild liver disease	1	571, 573.01, 573.04	B18, K70.0–K70.3, K70.9, K71, K73, K74, K76.0
Diabetes I and II	1	249.00, 249.06, 249.07, 249.09, 250.00, 250.06, 250.07, 250.09	E10.0, E10.1, E10.9, E11.0, E11.1, E11.9
Hemiplegia	2	334	G81, G82
Moderate to severe kidney disease	2	403, 404, 580–584, 590.09, 593.19, 753.10–753.19, 792	I12, I13, N00–N05, N07, N11, N14, N17–N19, Q61
Diabetes with end organ damage	2	249.01–249.05, 249.08, 250.01–250.05, 250.08	E10.2–E10.8, E11.2–E11.8
Any tumor	2	140–194	C00–C75
Leukemia	2	204–207	C91–C95
Lymphoma	2	200–203, 275.59	C81–C85, C88, C90, C96
Moderate to severe liver disease	3	070.00, 070.02, 070.04, 070.06, 070.08, 573.00, 456.00–456.09	B15.0, B16.0, B16.2, B19.0, K70.4, K72, K76.6, I85
Metastatic solid tumor	6	195–199	C76–C80
AIDS	6	079.83	B21–B24

Table S2 Diagnosis codes for myocardial infarction according to the International Classification of Diseases, 8th (ICD-8) and 10th (ICD-10) revision

Myocardial infarction	ICD-8 codes	ICD-10 codes
Prior to the scan	410	I21, I22, I23
Outcome	410	I21

Table S3 Risk and hazard ratio of MI and all-cause death within 5 years following a normal versus abnormal scan

					Hazard ratio (95% CI)
Outcome	Scan result	No. of events	Risk % (95% CI)	Risk difference % (95% CI)	Unadjusted	Adjusted*
MI	Normal	22	11.4 (7.2 – 16.7)	8.1 (1.9 – 14.2)	1 (reference)	1 (reference)
		Abnormal	85	19.4 (15.9 – 23.3)	1.64 (1.03 – 2.62)	1.53 (0.95 – 2.47)
All-cause death	Normal	14	7.9 (4.7 – 13.0)	3.9 (−1.1 – 8.9)	1 (reference)	1 (reference)
		Abnormal	50	11.8 (9.1 – 15.3)	1.48 (0.82 – 2.67)	1.19 (0.65 – 2.17)

Note: Included are patients with a first-time MI 0−1 year before the scan. *Adjusted for sex, age, and comorbidity level.

Abbreviations: CI, confidence interval; MI, myocardial infarction.

Table S4 Risk and hazard ratio of MI and all-cause death within 5 years following a normal versus abnormal scan.

					Hazard ratio (95% CI)
Outcome	Scan result	No. of events	Risk % (95% CI)	Risk difference % (95% CI)	Unadjusted	Adjusted*
MI	Normal	19	11.4 (6.8 – 17.2)	5.6 (−1.1 – 12.3)	1 (reference)	1 (reference)
		Abnormal	64	17.0 (13.4 – 21.0)	1.62 (0.97 – 2.70)	1.57 (0.93 – 2.65)
All-cause death	Normal	13	8.2 (4.8 – 13.7)	6.6 (0.9 – 12.2)	1 (reference)	1 (reference)
		Abnormal	54	14.8 (11.5 – 18.8)	1.88 (1.03 – 3.45)	1.56 (0.84 – 2.89)

Note: Included are patients with a first-time MI >1−5 years before the scan. *Adjusted for sex, age, and comorbidity level.

Abbreviations: CI, confidence interval; MI, myocardial infarction.