Cluster Subcutaneous Allergen Immunotherapy as a Sustainable
Practice Towards Net Zero Healthcare
To the Editor,
As the health care sector accounts for approximately 5% of global
greenhouse-gases (GHG) emissions, several health systems are calling for
adoption of transparent and standardized metrics for GHG accounting,
paving the way towards net zero healthcare [1]. Although allergen
immunotherapy (AIT) has been proposed as a prototype of individualized
medicine in terms of clinical response and safety for allergic disease,
commuting to medical facilities and lengthy build-up schedules have been
described as limiting factors to treatment compliance among subjects on
subcutaneous immunotherapy (SCIT) [2]. Cluster AIT schedules are
variations of conventional AIT regimes, in which the timeframe from
induction to maintenance phase is much shorter compared to conventional
AIT [3]. Hence, we assessed the contribution of a SCIT cluster
scheduled intervention in the reduction of the carbon footprint in
subjects starting SCIT.
In this single-center retrospective analysis, sociodemographic data,
clinical profile, the SCIT dosing schedule and the number of required
physical visits, and road travelled distance to our Institution during
the build-up phase of SCIT was collected from patients’ electronic
medical records (EMRs) from November 2021 to January 2022. Following
routine clinical practise, only subjects with a confirmed Allergist
SCIT-prescription, following a positive skin prick test and/or a
specific IgE (sIgE) to a corresponding panel of standardized
aeroallergen were included [4]. The investigation was approved by
the local Ethical Committee (institutional code CHUC 2022-13, on 2022,
February 24th).
A total of 710 doses of SCIT were administered in 145 patients during
the 12-week study period (Table 1S). All subjects successfully completed
a SCIT cluster protocol, including the administration of 2 injections at
a 30-minute interval in weekly visits to reach the maintenance dose in 1
to 4 weeks. A total of 97 out of 145 subjects (66.8%) completed a
cluster SCIT schedule with allergoids (adsorbed to aluminum hydroxide or
L-tyrosine and Glutaraldehyde-modified extracts), while 48 patients
(33.2%) followed a SCIT cluster regime with solely adsorbed to aluminum
hydroxide extracts. Regarding the composition of the prescribed SCIT,
the combination of House Dust Mites (HDM) was most frequently prescribed
in 64 out of 145 patients (44.13%), followed by HDM and Blomia
tropicalis in 50 subjects (34.48%). The mean number of required
physical visits per patient following a cluster schedule was
significantly (<0.001) reduced compared to a conventional SCIT
regime. The overall road travelled distance was 16,613 km for all 145
subjects completing a cluster SCIT schedule, in contrast to a total of
31,808 km following a conventional SCIT regime. In addition, the
estimated annual carbon footprint for the cluster schedule was 8,960 kg
Co2e with a potential reduction of 8,204 kg Co2e related to a
conventional SCIT regime (Figure 1) [5]. Ten adverse events (AE)
related to the cluster SCIT schedule were reported in 6 out of 145
patients (4.13%), increasing the mean (SD) number of outpatients
extra-visits to the Allergen Immunotherapy Unit (AIU) by 1.5±1.2 times
to reach the cluster SCIT maintenance dose. Nine out these 10 AEs were
described as mild non-immediate local reactions after subcutaneous
injection. The remaining AE was considered a Grade-II late moderate
reaction, successfully treated at home with the regular patient´s
medication after a telephone consultation to the AIU [6].
To our knowledge, this is the first study to investigate the
contribution of a cluster SCIT schedule in the reduction of the carbon
footprint related to scope 1 emissions as a part of our shared
responsibility to decarbonize (Figure 2). Health care professionals are
called to participate and implement sustainable medical practice
principles to routinely clinical practice. Cluster allergen SCIT may
contribute to reduce direct emissions from healthcare facilities to
achieve carbon neutrality.
References
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Figure 1: A) Contribution of cluster and conventional allergen
immunotherapy schedules to partial (CO2,
CH4, and NO2) and total
(CO2e) carbon footprint emissions from 2021 November to
2022 January. B) Annual CO2e of cluster and conventional
allergen immunotherapy schedules. Asterisks indicate statistical
significance (**** p<0.001).