Charlson Comorbidity scoring in ICD10 codes

This page explains how the actual Charlson Comorbidity Index is derived from the Charlson Comorbidities in ICD10 codes. See Charlson Comorbidity scoring in pre-ICD10 codes for the counterpart.

Short version

To get the Charlson comorbid points for a patient, use query L_ICD10_Charlson_score.

Long version

Points are not included in the listings because the score depends on the combination of diagnoses. For example, if a patient has two diagnoses from the same Charlson component, they are only counted once. Also, if a patient has diagnoses from a lesser and more severe component of the same type (e.g. Diabetes without and with complications), only the higher one counts.

The score is derived in a number of steps. CCMDB.accdb is the "master version" for the purposes of this calculation.

1. s_ICD10_Charlson_Como_patterns table contains matchable values and ranges of ICD10 codes assigned to Charlson comorbid groups; this was implemented as a set of ranges and matches rather than an absolute table to allow for future addition of ICD10 codes to fit into the Charlson calculation seamlessly and transparently, and most importantly, hands-off.
2. s_ICD10_Charlson_Como_conditions table contains the Charlson comorbid groups, their scores, and where applicable, groupings to show when one element takes precedence over another (e.g. if a pt has both cancer and metastatic cancer, only the score for metastatic cancer applies).
3. query s_ICD10_Charlson_Comorbids is the subset of diagnoses in s_ICD10 table that map to a match or range in s_ICD10_Charlson_Como_patterns table; it also includes the points from s_ICD10_Charlson_Como_conditions table
4. query L_ICD10_Charlson_dxs lists only the subset of the dxs coded in the L_ICD10 table that are also in query s_ICD10_Charlson_Comorbids
5. query L_ICD10_Charlson_component_points is an aggregate query which joins query L_ICD10_Charlson_dxs with the s_ICD10_Charlson_Como_conditions table; it keeps only the maximum score of each Charlson grouping
6. query L_ICD10_Charlson_score sums up the points in query L_ICD10_Charlson_component_points for the actual score for record / D_ID

This is then used by query Charlson_Score_pre_and_ICD10 to provide continuous Charlson Comorbidity Index scoring.