We conducted a cohort study including all registered patients at 706 general practices in the United Kingdom Clinical Practice Research Datalink, with 66.2 million person-years of follow-up from 2002 to 2017. There were 35,244 first episodes of
sepsis (17,886, 51%, female; median age 71 years, interquartile range 57-82 years). Consultations for
respiratory tract infection (RTI), skin or
urinary tract infection (UTI), and
antibiotic prescriptions were exposures. A Bayesian decision tree was used to estimate the probability (95% uncertainty intervals [UIs]) of
sepsis following an
infection consultation. Age, gender, and
frailty were evaluated as association modifiers. The probability of
sepsis was lower if an
antibiotic was prescribed, but the number of
antibiotic prescriptions required to prevent one episode of
sepsis (number needed to treat [NNT]) decreased with age. At 0-4 years old, the NNT was 29,773 (95% UI 18,458-71,091) in boys and 27,014 (16,739-65,709) in girls; over 85 years old, NNT was 262 (236-293) in men and 385 (352-421) in women.
Frailty was associated with greater risk of
sepsis and lower NNT. For severely frail patients aged 55-64 years, the NNT was 247 (156-459) in men and 343 (234-556) in women. At all ages, the probability of
sepsis was greatest for UTI, followed by skin
infection, followed by RTI. At 65-74 years, the NNT following RTI was 1,257 (1,112-1,434) in men and 2,278 (1,966-2,686) in women; the NNT following skin
infection was 503 (398-646) in men and 784 (602-1,051) in women; following UTI, the NNT was 121 (102-145) in men and 284 (241-342) in women. NNT values were generally smaller for the period from 2014 to 2017, when
sepsis was diagnosed more frequently. Lack of random allocation to
antibiotic therapy might have biased estimates; patients may sometimes experience
sepsis or receive
antibiotic prescriptions without these being recorded in primary care; recording of
sepsis has increased over the study period.
CONCLUSIONS: