TY - JOUR T1 - Should we cluster patients or symptoms? The myth of symptom clusters based on ‘depression, insomnia, pain’ and ‘depression, fatigue, pain’ JF - BMJ Supportive & Palliative Care JO - BMJ Support Palliat Care SP - 210 LP - 218 DO - 10.1136/bmjspcare-2015-000896 VL - 6 IS - 2 AU - Aynur Aktas AU - Declan Walsh AU - Katherine Hauser AU - Lisa Rybicki Y1 - 2016/06/01 UR - http://spcare.bmj.com/content/6/2/210.abstract N2 - Context ‘Depression, fatigue, pain’ (DFP) and ‘depression, insomnia, pain’ (DIP) symptom clusters (SCs) have been proposed in cancer. These symptoms are common and co-occur, that is, they constitute clusters of patients rather than symptoms.Objectives The following research questions were addressed: (1) What is the frequency of co-occurrence of two symptom groups (DFP and DIP) in advanced cancer? (2) What is the degree of symptom item association within each symptom group? (3) Were either of these symptom trios associated with prognosis?Methods We reanalysed a symptom data set of 1000 patients with advanced cancer. We identified the frequency of co-occurrence of two symptom groups: DFP and DIP, using both prevalence and severity data. The symptom associations were tested by χ2 and Spearman correlations. We also determined whether either of these symptom trios were associated with a major biological outcome, that is, survival by time-to-event analyses.Results (1) Although DFP and DIP co-occured in about a quarter of the population, they were not SCs, but rather patient clusters. (2) Many persons had only one symptom from any symptom pair, and correlation coefficients were low for all symptom pairs. (3) Neither DFP nor DIP were associated with survival.Conclusions Neither DFP nor DIP symptom item combinations constituted a specific cancer SC contrary to prior reports. DFP co-occurred in 27% and DIP in only 20%. Additionally, these symptom combinations were not associated with a biological outcome, that is, poor prognosis. Patient subgroups identified by shared symptom experiences alone do not identify SCs. ER -