Cough is a common symptom and is usually short term (acute) in nature. However, in some people, a cough can last for longer and a cough is defined as chronic if it lasts for eight weeks or more. The number of people with chronic cough in the UK has rarely been investigated.
The aim of the study is to select people with chronic cough. People who visit the GP with a long-term cough may not be recorded as having chronic cough. It will therefore be important to distinguish people with chronic cough from those who frequently visit their GP with acute cough caused by respiratory infections. Phase I of this study will select people with at least one record of cough between March 2014 and February 2015. We will determine whether the cough was recorded as acute, chronic or of unspecified duration. The number and the time between cough episodes within the study year will be investigated. Prescribed treatments and potential underlying causes will be determined. In Phase II, we will use these characteristics to select people who possibly have chronic cough. This research will enable us to ascertain who might benefit from any treatment developed for this condition.
In this retrospective cohort study, we aim to understand the epidemiology of cough and develop an algorithm to identify chronic cough. The study period will be from 1st March 2014 to 28th February 2015, with an observation period from 1st March 2013 to 29th February 2016 enabling cough episodes to be detected that start or end outside the study period. Research-quality patients will be selected if the later of their registration date and practice up-to-standard date occurs </=1st March 2013; they are alive on 1st March 2014; and the earlier of their transferring out (for reasons other than death) and last data-collection date occurs on or after 29th February 2016 (denominator population). In phase I of the study, people with one or more record of cough within the study period will be characterised in terms of their pattern of presentation and probable aetiology. In phase II, repeated cough records in CPRD will be grouped as episodes of possible recurrent or chronic cough using the information gathered in phase I. Data will be summarised using descriptive statistics. The period prevalence of chronic cough will be calculated by dividing the number of patients with chronic cough within the study period by the denominator population.
The pattern of cough presentation will be characterised as follows:
1. The number of people with a record for cough in the study period
2. The number of people with a Read code indicative of chronic cough recorded within the study period
3. The number of people with a record for cough within the wash-in period
4. The number of people with a Read code indicative of chronic cough recorded within the wash-in period
5. The mean number of cough diagnoses per person-year for the following periods:
a) Wash-in period
b) Study period
c) 1st March 2015 to 29th February 2016
6. The number of people with a record indicative of cough recorded within the wash-in or study period that is followed by one or more subsequent records more than 8 weeks after the first record but on or prior to the end of the observation period.
7. Distribution of the time between first Read or ICD-10 code indicative of cough recorded in the study period and all subsequent cough records prior to end of the observation period.
8. Distribution of the time between all Read or ICD-10 codes indicative of cough recorded within the wash-in period and the first cough diagnosis recorded in the study period.
9. Distribution of the time between index date and first outpatient attendance for those patients who are eligible for linkage to HES outpatient data.
10. The mean number of outpatient attendances per person-year for patients eligible for linkage to HES outpatient data for the following periods:
a) Wash-in period
b) Study period
c) 1st March 2015 to 29th February 2016
This will be calculated overall and by outpatient department.
11. Classification of the first cough record within the study period by:
a) Duration (as identified from the Read term or ICD-10 code description)
i. Acute
ii. Chronic
iii. Unspecified
b) Cough type (as identified from the Read term or ICD-10 code description)
i. Productive
ii. Dry
c) Potential underlying cause (as described below)
Haya Langerman - Chief Investigator - Merck Sharp & Dohme - UK
Sara Jenkins-Jones - Corresponding Applicant - Pharmatelligence Limited t/a Human Data Sciences
Alyn Morice - Collaborator - Hull York Medical School
Craig Currie - Collaborator - Cardiff University
Ellen Hubbuck - Collaborator - Pharmatelligence Limited t/a Human Data Sciences
Robert Boggs - Collaborator - Merck Sharp & Dohme - UK
Sarah Holden - Collaborator - Pharmatelligence Limited t/a Human Data Sciences
Surinder Birring - Collaborator - King's College London (KCL)
Ellen Hubbuck - Collaborator - Pharmatelligence Limited t/a Human Data Sciences
Sarah Holden - Collaborator - Pharmatelligence Limited t/a Human Data Sciences
HES Admitted Patient Care;HES Outpatient