Background
Methods
Patient recruitment
Interviews
Data analysis
Results
ID | Age | Sex | Patient preference SPT versus blood test | Occupation | Presenting problems | Previous allergy testing? (details, if known) | Recent allergy testing |
---|---|---|---|---|---|---|---|
A1 | 17 | M | SPT | Student | Rhino-conjunctivitis | Yes (SPT) | Blood test |
A2 | 27 | F | No preference | Credit control analyst | Suspected sea food allergy | Yes (SPT) | SPT |
A3 | 31 | M | SPT | Project manager | Seasonal rhinitis Food allergies (egg and nuts) | Yes (SPT & Blood test) | SPT & Blood test |
A4 | 23 | F | Blood test | Secretary | Venom anaphylaxis | No | Blood test |
A5 | 31 | M | Blood test | Financial advisor | Churg-Strauss syndrome –rhinitis, polyps | No | SPT |
A6 | 57 | M | SPT | Director of engineering company | Angioedema | No | SPT & Blood test |
A7 | 31 | M | SPT | Manual labourer | Perennial rhino-conjunctivitis | No | SPT |
A8 | 31 | M | SPT | Barber | Perennial and seasonal rhino-conjunctivitis | Yes (SPT) | SPT & Blood test |
A9 | 77 | F | SPT | Retired | Suspected latex allergy | No | SPT |
A10 | 32 | F | SPT | Accounts manager | Seasonal Rhinitis Oral allergy syndrome | No | SPT |
A11 | 40 | F | SPT | Freelance journalist | Seasonal and perennial rhinitis | No | SPT |
A12 | 75 | F | SPT | Retired | Suspected food allergy | Yes (Blood test) | SPT |
A13 | 43 | F | SPT | Graphic designer | Seasonal and perennial rhinitis | No | SPT |
A14 | 48 | F | SPT | Children’s social worker | Seasonal rhino-conjunctivitis | No | SPT |
A15 | 44 | F | Blood test | Nurse | Perennial rhinitis | No | SPT |
A16 | 60 | F | SPT | Nurse | Angioedema | Yes (SPT & Blood test) | SPT |
A17 | 22 | F | SPT | Student | Asthma triggered by cat exposure | No | SPT |
A18 | 42 | F | SPT | Media/PR agency (3) | Asthma and rhinitis Suspected sea food allergy | No | SPT & Blood test |
A19 | 28 | M | SPT | Chef | Seasonal rhinitis Oral allergy syndrome | Yes (SPT) | SPT |
A20 | 31 | M | SPT | Political campaign officer | Perennial rhino-conjunctivitis | No | SPT |
A21 | 23 | M | SPT | Retailer | Difficult to control asthma | No | SPT and Blood test |
A22 | 41 | M | Blood test | Painter and decorator | Asthma, suspected dog allergy | No | SPT & Blood test |
A23 | 58 | F | No preference | Voluntary financial work | Anaphylaxis, suspected nut allergy | Yes (SPT) | SPT & Blood test |
Understanding of skin prick testing procedure
‘Well I’d only ever heard about the, the, when they put the thing on your forearm. I didn’t realise it was a pinprick, I though they just put a bit of solution, they put on there and done you that way.’ (Male, 41)‘I knew that I was going to have little drops on my arms, but I didn’t know that they were going to scratch the surface ……’ (Female, 43)
‘I thought someone was going to scrape a bit of my skin off and take a bit of blood, that’s what I thought.’ (Male, 31)
The SPT procedure
‘Marked my arm with that strip and then put the drops of each thing on and then used the needle to prick the skin and then sat me in the waiting room. Waited for a while and then called me into check whether I had reacted to anything, which I hadn’t….’ (Male, 31)
‘it was like I’d been bitten by a million ants or something, it was pretty intense, having 10 needles all at once, but it wasn’t unbearable, it was you know, I knew it was going to happen.’ (Female, 32)‘well I think that was the most, the most discomfort I’ve had, being in the allergy clinic, that part, it, I thought I didn’t like it at all.’ (Male, 41)
‘I was a bit concerned sometimes when the skin was being pricked. I was a bit concerned as to whether some of those things that you use to prick were pricky enough. I felt some of them and I didn’t feel some of the other ones. So some were actually I could feel them pricking me where others I didn’t feel prick me and I almost thought that it wasn’t done hard enough, if that makes sense?So my trust in the process was a little bit wary.’ (Male, 31)
Longer term discomfort
‘You know it’s not really nice feeling, its irritation obviously.’ (Male, 28)‘It, it was fine. I mean it was really itchy afterwards, but the actual test was fine’ (Male, 23)
Interpretation of SPT
‘I liked the fact that you could see what you reacted to so it was very obvious that you had a reaction to them rather than someone just telling you, you are allergic to something’. (Male, 31)
‘That was quite a good way of illustrating the allergy.’ (Male, 31)‘I reacted quite badly to the dust….blatantly obvious how bad it was, and it prompted us to rip up our carpets for example, and get laminate flooring so it doesn’t hold the dust in the room, and that kind of thing.’ (Male, 23)
Opportunity to discuss test results
The interpretation of a wheal as sensitisation not allergy was also confusing to some. One patient asked:‘….I’m increasingly reacting to fruits and hazelnuts, um skin tests didn’t detect that I was allergic to the, um because I’m allergic to pollen the suggestions was that the pollen gets into the fruit and the hazelnuts and that could cause me to react, so um that’s kind of useful information.’ (Male, 31)
‘Does that mean I am a little bit allergic to salmon, to cod, to the, to the, to the, but I mean I eat that on a daily basis.’ (Female, 27)
In vitro testing experiences
Blood taking process
Some respondents described a degree of physical pain, ‘not too bad’, ‘just mild discomfort’. Discussing their venepuncture for in vitro allergy testing prompted memories of previous blood sampling, respondents often digressing to recall less than optimal experiences of locating a vein or the resultant bruising. Some respondents described their coping strategies for venepuncture ‘I look away and don’t watch the needle go in’ (Male, 31). Others alluded to emotional rather than physical discomfort, ‘No forewarning, I was wearing a top that I had to take off’ in an area she perceived as communal. (Female, 58)‘It was fairly good, fairly fast and it didn’t hurt or anything.’ (Male, 17)‘It didn’t take longer than 2 min.’ (Male, 31)
Delay receiving blood test results
However, this delay was not always perceived as negative, one lady described how it gave her time to acclimatise ‘…it was all quite new and frightening so I wasn’t really in a hurry [to know]….’ (Female, 23).…it doesn’t take much time, but with the blood test it take a few weeks to get the results back.’ This respondent went on to comment on the impact of the results ‘….and you don’t see it for yourself so you’re obviously relying on someone else to you know, make the judgement about whether you reacted to it. …. there’s still that slight doubt in my mind that I may react to them…. Information can get lost in translation.’ (Male, 31)
Perceived strengths of the different test modalities
This perception of superiority of in vitro testing was sufficient for some interviewees to reflect on their willingness to tolerate pain or overcome needle phobia for a better test:‘I mean the prick test, as I said, it’s a very simple one, and the blood test is probably a more in depth test.’ (Female, 27)‘I think that a blood test is more accurate because it’s kind of part of you, more than just a few dots on a skin prick test. I think it can find out really what is wrong with you.’ (Female, 23)
Three respondents (two nurses and one financial adviser) spontaneously brought up issues relating to the efficiency of the two testing modalities, making a comparison between ‘one injection’ and the very visible multi-stage process of SPT with lancet pricks, waiting, and clinical interpretation and feedback. They wondered whether venepuncture was ‘more efficient from the NHS’ point of view’. One respondent commented:‘I mean I hate blood tests, but if having a blood tests means that I would know what definite, you know I am allergic to then I will do it.’ (Female, 27)
Qualitative research does not generally seek to enumerate, but at the close of the interview respondents were asked to comment on their preference for allergy test modality. Some patients were very decisive; others hesitated before coming to a conclusion, explaining that their desire to confirm or exclude an allergic trigger may override any perceived disadvantage of the allergy test.‘…. [in vitro testing] may be cost saving, to give a vial of blood that goes off, to haematology or whichever department will look at it, and they’ll go do their tests. And so you haven’t got loads of people running round measuring things, pricking arms, sending you back into the waiting room, sending you back in again.’ (Female, 60)
Seventeen of the 23 patients finally expressed a preference for SPT and four for in vitro testing. The remaining two had ‘no strong feelings either way’ and perceived the two testing modalities as equivalent. Of the ten participants who had experience of both in vivo and in vitro allergy testing, eight expressed a preference for skin prick testing, one for venepuncture and one expressed no preference. This distribution of expressed preferences was mirrored in those who had only theoretical knowledge of one or other of the allergy testing modalities.‘So I wouldn’t mind either of them to be honest. As long as it does, you know it does tell me what is my problem.’ (Female, 27)