Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Autoimmune diseases have been observed in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN); however, acquired hemophilia, which can develop owing to autoimmune diseases, has not yet been reported SJS/TEN patients. A 74-yearold male patient, who had been treated for SJS after allopurinol exposure, was referred to our clinic due to hypotension and mucosal erosions. He was suspected to have septic shock due to widespread mucosal involvement caused by SJS, which improved after 1week of intensive conservative treatment that included antibiotics and systemic corticosteroids. However, a rapid increase in prothrombin time (> 60 seconds) and activated partial thromboplastin time (> 120 seconds) was confirmed, and the mixture of the 2materials did not improve decreased factor VIII activity (18.7%). The patient was diagnosed with acquired hemophilia, which was probably associated with SJS. In this case, acquired hemophilia, a fatal and rare autoimmune disease, occurred concurrently with SJS.

Autoimmune diseases have been observed in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN); however, acquired hemophilia, which can develop owing to autoimmune diseases, has not yet been reported SJS/TEN patients. A 74-yearold male patient, who had been treated for SJS after allopurinol exposure, was referred to our clinic due to hypotension and mucosal erosions. He was suspected to have septic shock due to widespread mucosal involvement caused by SJS, which improved after 1week of intensive conservative treatment that included antibiotics and systemic corticosteroids. However, a rapid increase in prothrombin time (> 60 seconds) and activated partial thromboplastin time (> 120 seconds) was confirmed, and the mixture of the 2materials did not improve decreased factor VIII activity (18.7%). The patient was diagnosed with acquired hemophilia, which was probably associated with SJS. In this case, acquired hemophilia, a fatal and rare autoimmune disease, occurred concurrently with SJS.

Autoimmune diseases have been observed in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN); however, acquired hemophilia, which can develop owing to autoimmune diseases, has not yet been reported SJS/TEN patients. A 74-yearold male patient, who had been treated for SJS after allopurinol exposure, was referred to our clinic due to hypotension and mucosal erosions. He was suspected to have septic shock due to widespread mucosal involvement caused by SJS, which improved after 1week of intensive conservative treatment that included antibiotics and systemic corticosteroids. However, a rapid increase in prothrombin time (> 60 seconds) and activated partial thromboplastin time (> 120 seconds) was confirmed, and the mixture of the 2materials did not improve decreased factor VIII activity (18.7%). The patient was diagnosed with acquired hemophilia, which was probably associated with SJS. In this case, acquired hemophilia, a fatal and rare autoimmune disease, occurred concurrently with SJS.

Autoimmune diseases have been observed in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN); however, acquired hemophilia, which can develop owing to autoimmune diseases, has not yet been reported SJS/TEN patients. A 74-yearold male patient, who had been treated for SJS after allopurinol exposure, was referred to our clinic due to hypotension and mucosal erosions. He was suspected to have septic shock due to widespread mucosal involvement caused by SJS, which improved after 1week of intensive conservative treatment that included antibiotics and systemic corticosteroids. However, a rapid increase in prothrombin time (> 60 seconds) and activated partial thromboplastin time (> 120 seconds) was confirmed, and the mixture of the 2materials did not improve decreased factor VIII activity (18.7%). The patient was diagnosed with acquired hemophilia, which was probably associated with SJS. In this case, acquired hemophilia, a fatal and rare autoimmune disease, occurred concurrently with SJS.

Autoimmune diseases have been observed in patients with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN); however, acquired hemophilia, which can develop owing to autoimmune diseases, has not yet been reported SJS/TEN patients. A 74-yearold male patient, who had been treated for SJS after allopurinol exposure, was referred to our clinic due to hypotension and mucosal erosions. He was suspected to have septic shock due to widespread mucosal involvement caused by SJS, which improved after 1week of intensive conservative treatment that included antibiotics and systemic corticosteroids. However, a rapid increase in prothrombin time (> 60 seconds) and activated partial thromboplastin time (> 120 seconds) was confirmed, and the mixture of the 2materials did not improve decreased factor VIII activity (18.7%). The patient was diagnosed with acquired hemophilia, which was probably associated with SJS. In this case, acquired hemophilia, a fatal and rare autoimmune disease, occurred concurrently with SJS.