Abstract
We thank Dr. Smith for the interest in our article “Prevalence and socio-demographic characteristics of persons who have never had a headache among healthy voluntary blood donors – a population-based study” (1) and for the important comments and suggestions for future research.
Our study is the first to home in on individuals who have never experienced headache. As we are proposing a new phenotypic trait, it is debatable how to best define and capture individuals who have never experienced headache. The assessment of headache from a simple point of view holds the potential to capture the left tail of a headache frequency and severity distribution, see Figure 1. We agree with Dr. Smith that using self-reported data among other biases introduces the risk of word-selection bias and cognitive belief bias. Regarding other headache traits, we find that the prevalence of migraine among Danish blood donors resembles that of the general Danish population (2).
Theoretical distribution of headache and severity in a given population, with the proportional size of individuals who have never experience headache indicated in grey.
We fully acknowledge, as outlined by Dr. Smith, that the impact of gender on pain is challenging to interpret, but hopefully we will gain novel insight in the pain field from new rating scales like the Sensation and Pain rating Scale (3).
As pointed out by Dr Smith, validating the screening question is important. It is therefore a part of our current plan to validate the question together with analyzing sensitivity and pain perception of individuals who have never experienced headache. We are conducting clinical trials on a small subset of participants in the Danish Blood Donor Study, clinicaltrials.gov: NCT04217616 and NCT04217668. Here we are using a battery of different sensitivity and pain measurements (heat and cold pain threshold and total tenderness score) and conditioning pain stimuli (cold pressure test and headache provocation by isosorbide-mononitrate) in a case-control design (4–6). We hope that these trials will give us insight into the phenotype and provide us with enough data to address validity of the trait. The data is still blinded, so we cannot share any results yet.
We hope that other research groups are interested in the concept of a new headache trait and we are excited to see what we can learn about headache and pain from this new approach.
Footnotes
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
