Improving multimorbidity measurement using individualized disease-specific quality of life impact assessments: predictive validity of a new comorbidity index

Table 1 Summary and description of QDIS-MCC, legacy, and Charlson impact estimation methods and models compared

Model & MCC Estimation Method		Base	Count	Pop. weights	Ind. QDIS items	Description of MCC Impact Score (MCCIS)
QDIS-MCC Models
0	Base model—sociodemographics only	X
1	Simple chronic conditions count	X	X			Count of all reported conditions on expanded checklist
2–M/P	Population-weighted MCS/PCS score	X		X		Separate regressions for MCS & PCS on 35 (0/1) conditions in developmental sample; weighted sum of all reported conditions using corresponding MCS/PCS population weights
3	Individualized QDIS-weighted MCC score	X			X	Separate regressions for MCS/PCS, individualized by adding global QDIS ratings for all reported conditions (for each participant)
Charlson Models
1C	Charlson 12 count	X	X			Sum of all reported Charlson conditions
2C–M/P	MCS-/PCS- weighted Charlson score	X		X		Separate regressions for MCS & PCS on 12 (0/1) Charlson conditions in developmental sample; weighted sum of all reported Charlson conditions using corresponding MCS or PCS population weights
3C	Individualized QDIS-weighted Charlson	X			X	Separate regressions for MCS & PCS; individualized by adding global QDIS ratings for all reported Charlson conditions (for each participant)
4C	Mortality-weighted Charlson score	X		X		Pseudo-Charlson score for 12 conditions using 1987 published mortality rates

MCC = multiple chronic conditions, pop. = population, ind. = individualized, PCS = Short Form-8 Physical Component Score, MCS = Short Form-8 Mental Component Score
Model contrasts include:
0 vs. 1 or 1C: Sociodemographic-only base model (0) versus expanded 35-condition checklist (1) or Charlson 12 condition count (1C)
1 vs. 2-M/P: Expanded checklist condition count (1) versus population QOL weights for expanded checklist conditions (2-M/2-P)
1C vs. 2C-M/P: Charlson 12 count (1C) versus population QOL weights for Charlson 12 conditions (2C-M/2C-P)
2-M/P vs. 3: Population-weighted QOL (2-M/2-P) versus individualized QDIS ratings for expanded condition checklist (3)
2C-M/P vs. 3C: Test of population-weighted QOL versus individualized QDIS ratings for Charlson 12 conditions
4C vs. 3C: Test of mortality-weighted Charlson versus individualized QDIS ratings for Charlson 12 conditions

ISSN: 1477-7525