Background and aims
Frailty is a complex situation, characterized by a deterioration of multiple physiological systems. The appearance of breakthrough pain (BTP) in frail patients has a significant impact on their quality of life (QOL). The aim of the study was to analyze the clinical and social characteristics of frail patients with BTP.
Methods
A cross-sectional, observational, multicentre study was conducted, involving frail adult patients (Frail-scale score≥3), with adequately controlled baseline pain and diagnosis of BTP. The socio-demographic characteristics, socio-family assessment (Gijón scale), Karnofsky Performance Status (KPS), comorbidities, QOL (EuroQoL-5D-5L) and characteristics of chronic pain and BTP were recorded.
Results
A total of 240 patients (mean age 68 years (24-91); 58.5%men) were included. The mean Frail scale score was 3.9 points (IC95% 3.8-4) with a mean KPS of 63.3% and a mean Gijón scale score of 4,9 points (IC95% 4,5-5,3). Most patients were oncologic (92.9%; n = 222).  Patients presented 3.8 episodes of BTP/day with a mean duration of 34.1 minutes. The intensity of BTP was mild (3%), moderate (33.8%), intense (45.9%) and excruciating (17.3%). BTP was spontaneous 51.3% of the cases and appeared at night (12.6%) or during the day (38.5%). BTP was unpredictable in 65.4% of the patients. Pain was somatic (25.4%), visceral (22.9%), neuropathic (15.8%) and mixed (32.1%). Opioids were mainly (89.2%) the treatment of choice for BTP. 
Conclusions
To our knowledge this is the first study describing the clinical characteristics of frail patients with BTP. BTP characteristics did not differ from those described in non-frail patients.

ANALYSIS OF THE CLINICAL CHARACTERISTICS OF FRAIL PATIENTS WITH BREAKTHROUGH PAIN.