What is the difference between diagnosis-specific causal validity and causal validity of exposure variable?

Diagnosis-specific causal validity (level 2.3.8) tests whether multiple risk or related factors are causally linked to one particular diagnosis, usually through case-control studies. Causal validity of exposure variable (level 2.3.9) tests whether one etiological factor can causally influence a group of diagnoses, usually through exposure cohort studies, and can help establish causal chains or syndrome diagnoses.

Diagnosis-specific causal validity concerns the causal interpretation between multiple factors and a single diagnosis. Its evidence is based on case-control studies or similar methods that identify multiple risk or related factors for one diagnosis, with sufficient samples to measure the magnitude of effect. Diagnostic groups (case versus control) must be established using diagnostic accuracy measures from clinical construct validity studies. An example is identifying pressure ulcer risk factors in adults in intensive care. Causal validity of exposure variable concerns the causal interpretation between one etiological factor and a group of diagnoses. Its evidence comes from cohort studies or exposure cohort designs that compare an exposed group with a non-exposed group, with sufficient samples to measure risk magnitude. This type can establish importance of a factor for multiple diagnoses and can reveal causal chains or syndrome diagnoses. Each diagnosis in the group must already meet clinical construct validity criteria. An example is using an exposure cohort to assess fall risk in institutionalized elderly.