There were no significant differences in the median duration of cough : @ days among patients with CRP concentrations < @ mg/l -LSB- @ % confidence interval ( CI ) : @-@ days -RSB- , @ days among those with concentrations ranging from @ to @ mg/l ( @ % CI : @-@ ) and @ days in those with CRP > @ mg/l ( @ % CI : @-@ ) ( P = @ ) .