Prophylaxis reduces number of hereditary angioedema attacks requiring acute care
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Key takeaways:
- Of 463 recorded attacks, 238 doses of icatibant were administered for 212 attacks, and 75 doses of C1-INH IV were administered for 67 attacks.
- 23 attacks (5%) required an ED visit.
Patients with hereditary angioedema using modern prophylaxis had fewer attacks needing icatibant or C1-INH IV than patients on other therapies, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
These patients also reported fewer days lost than patients on other therapies, Constance H. Katelaris, MD, FRACP, PhD, head of department and senior staff specialist, immunology and allergy unit, Campbelltown Hospital, Sydney, New South Wales, Australia, and colleagues wrote.
“We wanted to capture details of patients’ HAE [hereditary angioedema] attacks and impacts on their lives in ‘real time’ rather than relying on retrospective surveys. Because we have limited access to prophylactic therapies, we wanted to see what difference being on a prophylactic therapy made to patients,” Katelaris told Healio.
The study enrolled 49 patients aged 14 to 90 years (mean age, 39.6 years; 34 females) with HAE and ran from July 2019 to November 2020.
Each Monday, patients received an SMS message asking them what medications they had used and if they had any attacks during the previous week. Patients who reported an attack received a follow-up phone call asking for more details.
Patients who did not respond to the SMS at all received a follow-up SMS on Thursday. When the researchers received responses to both questions, they considered it a confirmed week of observation.
The researchers sent 2,648 weekly SMS messages and received 1,892 responses for more than 436 months of total observational time and 9.1 months (range, 0.95-15.87) of average observational time.
Patients reported 463 attacks, with 212 attacks requiring 238 doses of icatibant including 19 attacks that required more than one dose. Also, 67 attacks required 75 doses measuring 500 IU, 1,000 IU or 1,500 IU of C1-INH IV concentrate.
Overall, nine patients went to the ED predominantly for facial and/or throat swelling in 23 attacks (5%), with one patient accounting for 11 of these attacks. Patients received icatibant after seven of these attacks before they went to the ED. C1-INH IV concentrate was used to treat 16 of these attacks before or during the ED visit.
Further, eight patients were receiving C1-INH IV concentrate, eight patients were receiving C1-INH SC concentrate, four were not receiving any treatment and the remainder were receiving danazol or tranexamic acid when these 23 attacks occurred.
There were 186 attacks reported by 103 patients that were not treated. According to the patients, 66% of these attacks were mild, 21% were moderate, 7% were severe or significant, 3% had no impact and 3% were unknown.
Twenty-two (46.8%) patients said they lost days of work, study or school because of attacks, including 59 (17%) attacks leading to 86 days (range, 0.5-7 days/attack) lost. Nearly half (49.5%) of these lost days were reported by patients who were not receiving prophylaxis and only used on-demand therapy.
Patients who used C1-INH IV concentrate reported 18 days lost, and patients who used C1-INH SC concentrate reported 11 days lost.
The 67 attacks experienced by the patients using C1-INH SC concentrate included two that occurred before treatment began, three recorded as incomplete data and five reported by a patient who withdrew from the study.
The 57 remaining attacks included 12 attacks reported by one patient over 7.6 months and 15 reported by another over 6.5 months. The other 30 attacks were attributed to 13 patients over 57.7 months.
Patients reported that SMS was convenient because they only had to recall the previous week and did not have to record information in lengthy diary entries, the researchers said. Overall, 30% of patients did not respond to messages because they did not have anything to report, they simply chose not to reply, or they were experiencing study fatigue.
The researchers noted that more than 75% of attacks led to acute therapy, whereas 22.5% of the patients did not use any acute treatment. Also, 33% of the patients who chose not to treat specific attacks did not treat attacks that were more severe than mild.
Specifically, patients did not use icatibant or C1-INH IV to self-manage their attacks because they thought the attack was mild, the attack had already gone on too long to use icatibant, they did not have access to treatment or they were reluctant to use treatment because of the cost.
“The significant finding was that those on prophylaxis fared better than those on on-demand treatment only — not surprising, but significant and important to document to help us advocate for greater access to these therapies,” Katelaris said.
“Secondly, we were surprised to find that a number of patients failed to treat significant attacks even though they had access to acute treatments,” she continued.
These findings suggest that patients may need further education about the importance of early treatment, the researchers said. Also, the researchers continued, further analysis is needed to understand why patients deem some treatment unnecessary and to assess the burden of not treating each acute attack.
Citing the improvements in attack rates with modern prophylactic therapy, the researchers called for prioritizing wider access to this treatment with reviews of dosages 2 months after initiation of care. Meanwhile, the researchers are continuing their work as well.
“We are collating a lot of quality-of-life data to give a more complete picture of impacts on patients,” Katelaris said.
For more information:
Constance H. Katelaris, MD, FRACP, PhD, can be reached at connie.katelaris@health.nsw.gov.au.
Perspective
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These findings are not surprising, as the HAE community is active online. SMS seems like an effective way to collect data. I have not employed SMS messaging for collecting data from my patients, as I do not have the bandwidth for that in a busy clinic. But I do expect that similar programs in the United States would achieve comparable results with these findings, which were in Australia.
Also, these findings showed that there may be better ways of tracking some chronic disease states — in particular, those that may have unpredictable and potentially life-threatening exacerbations. I think SMS helps patients increase their own awareness of their situation and could provide a more accurate reflection of whether they could be more optimally controlled or not.
There are currently apps available with which patients can easily track their HAE and its exacerbations. These data can be easily transferred to their doctor for review. Perhaps using the SMS model as a template, prompts or notifications could be developed inside the existing apps to enrich documentation and communication. This may provide an even more effective mechanism for tracking HAE patients.
It would be interesting to investigate if that tool actually made a difference in reducing attack frequency and severity by encouraging compliance with prophylactic medications and early treatment of all acute HAE attacks. I would like to see if that tool makes an actual difference in the patients’ control of their disease and their quality of life.
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