RT Journal A1 Brusius A, Zavascki AP, Costa S T1 HOw efficient is procalcitonin-guided antibiotic use in acute respiratory tract infections in primary care? JF Archives of Internal Medicine JO Archives of Internal Medicine YR 2009 FD July 13 VO 169 IS 13 SP 1241 OP 1247 DO 10.1001/archinternmed.2009.182 UL http://dx.doi.org/10.1001/archinternmed.2009.182 AB The antibiotic prescription for acute respiratory tract infection is still used with caution because there is no effective way to distinguish between viral and bacterial infection. Briel et al1 evaluated whether antibiotic therapy guided by procalcitonin reduces the use of antibiotics without increasing the restriction of activities experienced by patients compared with a standard therapy based on current guidelines. However, this primary end point—the restriction of activities as experienced by patients—is patient dependent and hard to replicate from one setting to another. It is not possible to capture its content and construct. Does it means work absence, no leisure time activity, lying in bed?