Cough presentation in primary care and the identification of chronic cough: a need for diagnostic clarity?

To investigate patterns of presentation of cough in primary care and develop an algorithm to identify probable and possible chronic cough (CC). This retrospective observational study used routine English primary care data and linked hospital data. Patients with ≥1 cough event in the study period (March 2014-February 2015) were selected. Index date was that of the earliest cough event in this period. Adults (aged ≥18 years) were classified as having probable CC if they had an explicit CC diagnosis; as having possible CC if they had ≥3 cough events recorded over 8-26 weeks; or, otherwise, as having acute cough. Underlying conditions associated with CC were identified. 198,151 people were identified. 56.5% were female; median age was 47.0 years. The prevalence of cough in the study year was 17.6%. Of the 150,213 identified adults, 1600 (1.1%), 10,913 (7.3%) and 137,718 (91.7%) were classified as having probable CC, possible CC or acute cough, respectively. Compared with probable CC and acute cough, a higher percentage of possible CC cases had a record on or prior to index date indicative of chronic obstructive pulmonary disease (30.6% versus 10.1% and 9.7%), gastro-esophageal reflux disease (32.6% versus 24.9% and 21.1%) or asthma (45.9% versus 27.6% and 27.9%). Prevalences of probable and possible CC were 0.18% and 1.2%, respectively. The prevalence of CC was lower than reported in previous studies. People with possible CC had higher rates of underlying conditions associated with CC. These observations may suggest poor recognition and/or under-recording of CC in primary care.