Table 3.
Observed Proportions of Patients in Risk Categories According to Definitions of Multimorbidity for the Primary Outcome of Hospital Readmission and/or Prolonged Length of Stay in the Derivation, Validation, and Total Cohortsa,b
| Definition of multimorbidity | Risk category |
||
|---|---|---|---|
| Low | Intermediate | High | |
| Derivation cohort (n=92,071) | |||
| ≥2 Body system categories and number of health conditions | 14,209 (15.8) | 35,782 (39.7) | 40,182 (44.5) |
| ≥2 Body system categories and number of chronic health conditions | 13,245 (14.4) | 45,445 (49.4) | 33,379 (36.2) |
| Number of distinct body system categories | 11,695 (12.7) | 39,632 (43.1) | 40,730 (44.2) |
| Number of CCS categories | 8640 (9.4) | 42,472 (46.1) | 40,949 (44.5) |
| Number of health conditions | 11,083 (12.3) | 38,861 (43.1) | 40,229 (44.6) |
| Number of chronic health conditions | 5995 (6.5) | 52,609 (57.1) | 33,465 (36.4) |
| Deyo-Charlson Comorbidity Index | 64,369 (69.9)c | 27,701 (30.1) | |
| Elixhauser-van-Walraven Comorbidity Index | 6798 (7.4) | 43,256 (47.0) | 42,016 (45.6) |
| Validation cohort (n=55,735) | |||
| ≥2 Body system categories and number of health conditions | 3799 (6.9) | 18,702 (34.2) | 32,193 (58.9) |
| ≥2 Body system categories and number of chronic health conditions | 3613 (6.5) | 26,851 (48.2) | 25,267 (45.3) |
| Number of distinct body system categories | 2893 (5.2) | 20,349 (36.5) | 32,489 (58.3) |
| Number of CCS categories | 1940 (3.5) | 22,419 (40.2) | 31,371 (56.3) |
| Number of health conditions | 2721 (5.0) | 19,767 (36.1) | 32,206 (58.9) |
| Number of chronic health conditions | 1479 (2.7) | 28,931 (51.9) | 25,321 (45.4) |
| Deyo-Charlson Comorbidity Index | 38,209 (68.6)c | 17,525 (31.4) | |
| Elixhauser-Van-Walraven Comorbidity Index | 4483 (8.0) | 23,847 (42.8) | 27,404 (49.2) |
| Total cohort (N=147,806) | |||
| ≥2 Body system categories and number of health conditions | 18,008 (12.4) | 54,484 (37.6) | 72,375 (50.0) |
| ≥2 Body system categories and number of chronic health conditions | 16,858 (11.4) | 72,296 (48.9) | 58,650 (39.7) |
| Number of distinct body system categories | 14,588 (9.9) | 59,981 (40.6) | 73,233 (49.5) |
| Number of CCS categories | 10,580 (7.2) | 64,891 (43.9) | 72,320 (48.9) |
| Number of health conditions | 13,804 (9.5) | 58,628 (40.5) | 72,435 (50.0) |
| Number of chronic health conditions | 7474 (5.0) | 81,540 (55.2) | 58,790 (39.8) |
| Deyo-Charlson Comorbidity Index | 102,578 (69.4)c | 45,226 (30.6) | |
| Elixhauser-van-Walraven Comorbidity Index | 11,281 (7.6) | 67,103 (45.4) | 69,421 (47.0) |
CCS = Clinical Classification Software.
Data are presented as percentages of the cohort. The low-, intermediate-, and high-risk categories were defined using the cutoffs identified in Table 2. Patients with a number of items lower than the lower cutoff were classified at low risk, those with a number higher than or equal to the upper cutoff at high risk, and those with a number between the lower and the upper cutoffs at intermediate risk. For example, for the number of health conditions, 0 to 2 health conditions corresponds to low risk, 3 to 8 health conditions to intermediate risk, and 9 or more health conditions to high risk of multimorbidity.
For the Deyo-Charlson Comorbidity Index, there were only 2 risk categories, as we could not identify a lower cutoff.