Clinical meaning
Prognostication involves estimating the probable course and outcome of a disease, including expected survival and functional trajectory. Three predominant illness trajectories have been described by Lunney and Lynn: (1) Cancer trajectory - relatively maintained function with rapid decline in the last weeks to months before death. This trajectory is the most 'predictable,' allowing earlier hospice referral and advance care planning. (2) Organ failure trajectory (HF, COPD, ESRD) - characterized by episodic exacerbations and recoveries with gradual overall decline. Each exacerbation carries risk of death, but patients may recover multiple times, making prognostication challenging. This trajectory pattern often delays palliative care referral because 'the patient might get better.' (3) Frailty/dementia trajectory - prolonged, gradual decline over years with progressive functional and cognitive loss. Death often occurs from complications (aspiration pneumonia, UTI, pressure injuries) rather than the primary diagnosis. Prognostic accuracy improves closer to death but is generally poor beyond 6 months. Clinician estimates are systematically optimistic (overestimate survival by a factor of 3-5). Validated prognostic tools improve accuracy: Palliative Performance Scale (PPS), Palliative Prognostic Score (PaP), Palliative Prognostic Index (PPI). Biomarkers...