Background Vocal cord dysfunction (VCD) is a debilitating condition characterised by paroxysmal episodes of dyspnoea, typically resulting from abnormal adduction of the vocal cords during breathing. Diagnosis is complicated by its self-limiting nature and significant overlap in symptoms with other respiratory conditions such as asthma, and referral for further investigation therefore requires a high index of suspicion from non-specialist physicians. Our aim is to design a questionnaire with a high positive predictive value for VCD, which would hopefully lead to earlier identification and treatment and also reduce the levels of iatrogenic morbidity associated with misdiagnosis.
Methods 15 subjects with a confirmed diagnosis of VCD were recruited from the outpatient respiratory department. Semi-structured interviews in four focus groups were conducted to capture each sufferer's subjective experience. Concurrently, two focus groups were held with nine healthcare professionals with specialist and non-specialist interest to gather professional opinion on VCD symptoms. The collated data were used to generate a preliminary questionnaire that was tested for face validity in ten patients and healthcare professionals.
Results (1) Item generation: symptom profiles varied markedly, however certain characteristics did emerge with commonalities between most of the subjects or within a specific subset of individuals. These were grouped into the following themes—location, onset, sensations, breathing/voice changes, triggers, exacerbating factors and psychosocial impact. 17 items were generated for the preliminary questionnaire and expressed as positive or negative statements. (2) Face validity: general response was positive towards the comprehensibility of the statements and relevance to each subject. Based on user comments the number of items was reduced to twelve, all items were modified to positive statements to improve comprehensibility and a 5-point analogue scale will be used for scoring responses.
Conclusions A preliminary diagnostic tool has been generated and tested for face validity in patients with VCD. Initial feedback indicates a high relevance of the questionnaire items to the subject. At this stage, modifications have been made to eliminate ambiguity and repetition. We will now test concurrent validity, specificity and test-retest variability of the questionnaire in healthy volunteers, and respiratory patients with and without VCD.
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