Indirect Morbidity of Venom Allergy measured by Venom-Allergy Quality of
Life Questionnaire (VQLQ) in Jack Jumper Ant Allergic Patients
Abstract
Background Insect Stings with the venoms of Hymenoptera species
are well recognized as leading directly to allergic reactions in
sensitised individuals. As with other hymenoptera venoms – Venom
specific allergen Immunotherapy (VIT) to Jack Jumper Ants (JJA)
Myrmecia pilosula has demonstrated efficacy in preventing the
direct morbidity associated with severe venom-associated allergic
reactions. Despite this, the indirect morbidity of severe allergy on
associated background health related quality of life (HR-QoL) has not
previously been assessed in patients with JJA venom allergy.
Materials and methods M pilosula venom-allergic patients
referred for treatment in a specialized quaternary venom treatment
centre were surveyed with a venom specific HR-QoL questionnaire before
and after receiving 12 months of allergen-specific venom-immunotherapy
(VIT) according to JJA. A smaller subgroup also repeated this
questionnaire after receiving JJA sting-challenge. Results 53
patients completed both pre-VIT and post-VIT QoL questionnaires. 83% of
these patients achieved a minimal important difference (MID) of
increased change in QoL of >0.5. Mean HR-QoL improved by
1.85, NNT = 1.2. There was no statistically significant difference when
stratified by index-reaction grade, but appeared to be greater
impairment, and subsequent improvement, Female vs Male. In the subgroup
of 22 patients surveyed after VIT & re-surveyed after supervised sting
challenge, Mean HR-QoL improvement 0.7, and 50% achieved a MID
>0.5; therefore giving a ‘Number needed to sting’ = 2.0.
Patients with the largest impairment in HR-QoL appeared to benefit the
most from sting-challenge. Conclusion In JJA venom allergy the
magnitude of indirect allergic morbidity, measured by HR-QoL, appears to
be a separate phenomenon to that of the direct morbidity of clinical
allergic sensitivity [as measured by index reaction grade.] Patient
factors including gender may be important considerations for this
indirect morbidity. As with direct allergic sensitivity, improvements in
indirect morbidity can also be obtained by VIT treatment. In addition,
formal supervised exposure with sting-challenge in patients may provide
additional improvements in those with significant persistent
allergy-related QoL impairment.