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Equations: Chronic Respiratory Disease

Again following GBD authors, IFs separately computes the two components of the chronic respiratory disease category–chronic obstructive pulmonary disease (COPD) (where smoking is the overwhelming related risk factor) and “other” respiratory disease (where smoking is somewhat less determinative). Both elements follow the same formulation:

CRD equation 1

CRD equation 2

SIR is the “smoking impact ratio, ”  that is smoking impact in IFs (HLSMOKINGIMP) divided by an adjustment factor that is specific to three big regions (1. China, 2. World, and 3. SearD (Bangladesh, Bhutan, India, North Korea, Maldives, Myanmar, Nepal, Afghanistan, Pakistan)), [1]   age category c, gender p. CRDRR is the relative risk for chronic respiratory disease specific to age category c, gender p, and disease/death d type (COPD or other respiratory disease). [2]   Chronic respiratory disease is assumed to be declining at 75 percent of ONCD_Mort, which is other Group II related mortality.


[1] GBD authors provided the adjustment factor for SIR, and it is constant over the length of the IFs forecast. The computation is done with the hard-code value in a procedure called UpdateRespDisease.  The name for SmokingImpactAdj in the model is sird.  CRDRR is hard-code in the same procedure.

[2] RR ranges from approximately 10 for COPD to about 2 for other chronic causes.  Again, GBD authors provided the relative risk estimates used in IFs.