Commentary: Studies Often Do Not Answer Clinical Questions in AD, May 2024

In "Atopic Dermatitis in Early Childhood and Risk of Inflammatory Bowel Disease: A Scandinavian Birth Cohort Study," Lerchova and colleagues found a statistically significant increased risk for inflammatory bowel disease (IBD) in children with atopic dermatitis. The study had a large patient population, giving it the power to identify very small differences. The researchers found increased risks for IBD, Crohn's disease, and ulcerative colitis (UC) in children with atopic dermatitis; UC had the greatest relative risk. But I don't think this risk was clinically meaningful. About 2 in every 1000 children with atopic dermatitis had UC, whereas about 1 in every 1000 children without atopic dermatitis had UC. Even if the increased absolute risk of 1 in 1000 children was due to atopic dermatitis and not to other factors, I don't think it justifies the authors' conclusion that "these findings might be useful in identifying at-risk individuals for IBD."

Sometimes reviewing articles makes me feel like a crotchety old man. A study by Guttman-Yassky and colleagues, "Targeting IL-13 With Tralokinumab Normalizes Type 2 Inflammation in Atopic Dermatitis Both Early and at 2 Years," didn't seem to test any specific hypothesis. The researchers just looked at a variety of inflammation markers in patients with atopic dermatitis treated with tralokinumab, an interleukin-13 (IL-13) antagonist. In these patients, as expected, the atopic dermatitis improved; so did the inflammatory markers. Did we learn anything clinically useful? I don't think so. We already know that IL-13 is important in atopic dermatitis because when we block IL-13, atopic dermatitis improves.

Vitamin D supplementation doesn't appear to improve atopic dermatitis, as reported by Borzutzky and colleagues in "Effect of Weekly Vitamin D Supplementation on the Severity of Atopic Dermatitis and Type 2 Immunity Biomarkers in Children: A Randomized Controlled Trial." A group of 101 children with atopic dermatitis were randomly assigned to receive oral vitamin D supplementation or placebo. The two groups improved to a similar extent. If you know me, you know I'm wondering whether they took the medication. It appears that they did, because at baseline most of the children were vitamin D deficient, and vitamin D levels improved greatly in the group treated with vitamin D but not in the placebo group.

Journals such as the Journal of the American Academy of Dermatology should require articles to report absolute risk. In "Risk of Lymphoma in Patients With Atopic Dermatitis: A Case-Control Study in the All of Us Database," Powers and colleagues tell us that atopic dermatitis is associated with a statistically significantly increased risk for lymphoma. This means that increased risk wasn't likely due to chance alone. The article says nothing, as far as I could tell, about how big the risk is. Does everyone get lymphoma? Or is it a one in a million risk? Without knowing the absolute risk, the relative risk doesn't tell us whether there is a clinically meaningful increased risk or not. I suspect the increased risk is small. If the incidence of lymphoma is about 2 in 10,000 and peripheral T-cell lymphomas (PTCL) account for 10% of those, even a fourfold increase in the risk for PTCL (the form of lymphoma with the highest relative risk) would not amount to much. 

Traidl and colleagues report in "Treatment of Moderate-to-Severe Atopic Dermatitis With Baricitinib: Results From an Interim Analysis of the TREATgermany Registry" that the Janus kinase inhibitor baricitinib makes atopic dermatitis better. 

In "Dupilumab Therapy for Atopic Dermatitis Is Associated With Increased Risk of Cutaneous T Cell Lymphoma," Hasan and colleagues report that "it requires 738 prescriptions of dupilumab to produce one case of CTCL [cutaneous T-cell lymphoma]." It seems that this finding could easily be due to 1 in 738 people with a rash thought to be severe atopic dermatitis needing dupilumab having CTCL, not atopic dermatitis, to begin with. If we were to wonder whether dupilumab causes CTCL, perhaps it would be better to study asthma patients treated with or without dupilumab.
 

In "Atopic Dermatitis in Early Childhood and Risk of Inflammatory Bowel Disease: A Scandinavian Birth Cohort Study," Lerchova and colleagues found a statistically significant increased risk for inflammatory bowel disease (IBD) in children with atopic dermatitis. The study had a large patient population, giving it the power to identify very small differences. The researchers found increased risks for IBD, Crohn's disease, and ulcerative colitis (UC) in children with atopic dermatitis; UC had the greatest relative risk. But I don't think this risk was clinically meaningful. About 2 in every 1000 children with atopic dermatitis had UC, whereas about 1 in every 1000 children without atopic dermatitis had UC. Even if the increased absolute risk of 1 in 1000 children was due to atopic dermatitis and not to other factors, I don't think it justifies the authors' conclusion that "these findings might be useful in identifying at-risk individuals for IBD."

Sometimes reviewing articles makes me feel like a crotchety old man. A study by Guttman-Yassky and colleagues, "Targeting IL-13 With Tralokinumab Normalizes Type 2 Inflammation in Atopic Dermatitis Both Early and at 2 Years," didn't seem to test any specific hypothesis. The researchers just looked at a variety of inflammation markers in patients with atopic dermatitis treated with tralokinumab, an interleukin-13 (IL-13) antagonist. In these patients, as expected, the atopic dermatitis improved; so did the inflammatory markers. Did we learn anything clinically useful? I don't think so. We already know that IL-13 is important in atopic dermatitis because when we block IL-13, atopic dermatitis improves.

Vitamin D supplementation doesn't appear to improve atopic dermatitis, as reported by Borzutzky and colleagues in "Effect of Weekly Vitamin D Supplementation on the Severity of Atopic Dermatitis and Type 2 Immunity Biomarkers in Children: A Randomized Controlled Trial." A group of 101 children with atopic dermatitis were randomly assigned to receive oral vitamin D supplementation or placebo. The two groups improved to a similar extent. If you know me, you know I'm wondering whether they took the medication. It appears that they did, because at baseline most of the children were vitamin D deficient, and vitamin D levels improved greatly in the group treated with vitamin D but not in the placebo group.

Journals such as the Journal of the American Academy of Dermatology should require articles to report absolute risk. In "Risk of Lymphoma in Patients With Atopic Dermatitis: A Case-Control Study in the All of Us Database," Powers and colleagues tell us that atopic dermatitis is associated with a statistically significantly increased risk for lymphoma. This means that increased risk wasn't likely due to chance alone. The article says nothing, as far as I could tell, about how big the risk is. Does everyone get lymphoma? Or is it a one in a million risk? Without knowing the absolute risk, the relative risk doesn't tell us whether there is a clinically meaningful increased risk or not. I suspect the increased risk is small. If the incidence of lymphoma is about 2 in 10,000 and peripheral T-cell lymphomas (PTCL) account for 10% of those, even a fourfold increase in the risk for PTCL (the form of lymphoma with the highest relative risk) would not amount to much. 

Traidl and colleagues report in "Treatment of Moderate-to-Severe Atopic Dermatitis With Baricitinib: Results From an Interim Analysis of the TREATgermany Registry" that the Janus kinase inhibitor baricitinib makes atopic dermatitis better. 

In "Dupilumab Therapy for Atopic Dermatitis Is Associated With Increased Risk of Cutaneous T Cell Lymphoma," Hasan and colleagues report that "it requires 738 prescriptions of dupilumab to produce one case of CTCL [cutaneous T-cell lymphoma]." It seems that this finding could easily be due to 1 in 738 people with a rash thought to be severe atopic dermatitis needing dupilumab having CTCL, not atopic dermatitis, to begin with. If we were to wonder whether dupilumab causes CTCL, perhaps it would be better to study asthma patients treated with or without dupilumab.
 

In "Atopic Dermatitis in Early Childhood and Risk of Inflammatory Bowel Disease: A Scandinavian Birth Cohort Study," Lerchova and colleagues found a statistically significant increased risk for inflammatory bowel disease (IBD) in children with atopic dermatitis. The study had a large patient population, giving it the power to identify very small differences. The researchers found increased risks for IBD, Crohn's disease, and ulcerative colitis (UC) in children with atopic dermatitis; UC had the greatest relative risk. But I don't think this risk was clinically meaningful. About 2 in every 1000 children with atopic dermatitis had UC, whereas about 1 in every 1000 children without atopic dermatitis had UC. Even if the increased absolute risk of 1 in 1000 children was due to atopic dermatitis and not to other factors, I don't think it justifies the authors' conclusion that "these findings might be useful in identifying at-risk individuals for IBD."

Sometimes reviewing articles makes me feel like a crotchety old man. A study by Guttman-Yassky and colleagues, "Targeting IL-13 With Tralokinumab Normalizes Type 2 Inflammation in Atopic Dermatitis Both Early and at 2 Years," didn't seem to test any specific hypothesis. The researchers just looked at a variety of inflammation markers in patients with atopic dermatitis treated with tralokinumab, an interleukin-13 (IL-13) antagonist. In these patients, as expected, the atopic dermatitis improved; so did the inflammatory markers. Did we learn anything clinically useful? I don't think so. We already know that IL-13 is important in atopic dermatitis because when we block IL-13, atopic dermatitis improves.

Vitamin D supplementation doesn't appear to improve atopic dermatitis, as reported by Borzutzky and colleagues in "Effect of Weekly Vitamin D Supplementation on the Severity of Atopic Dermatitis and Type 2 Immunity Biomarkers in Children: A Randomized Controlled Trial." A group of 101 children with atopic dermatitis were randomly assigned to receive oral vitamin D supplementation or placebo. The two groups improved to a similar extent. If you know me, you know I'm wondering whether they took the medication. It appears that they did, because at baseline most of the children were vitamin D deficient, and vitamin D levels improved greatly in the group treated with vitamin D but not in the placebo group.

Journals such as the Journal of the American Academy of Dermatology should require articles to report absolute risk. In "Risk of Lymphoma in Patients With Atopic Dermatitis: A Case-Control Study in the All of Us Database," Powers and colleagues tell us that atopic dermatitis is associated with a statistically significantly increased risk for lymphoma. This means that increased risk wasn't likely due to chance alone. The article says nothing, as far as I could tell, about how big the risk is. Does everyone get lymphoma? Or is it a one in a million risk? Without knowing the absolute risk, the relative risk doesn't tell us whether there is a clinically meaningful increased risk or not. I suspect the increased risk is small. If the incidence of lymphoma is about 2 in 10,000 and peripheral T-cell lymphomas (PTCL) account for 10% of those, even a fourfold increase in the risk for PTCL (the form of lymphoma with the highest relative risk) would not amount to much. 

Traidl and colleagues report in "Treatment of Moderate-to-Severe Atopic Dermatitis With Baricitinib: Results From an Interim Analysis of the TREATgermany Registry" that the Janus kinase inhibitor baricitinib makes atopic dermatitis better. 

In "Dupilumab Therapy for Atopic Dermatitis Is Associated With Increased Risk of Cutaneous T Cell Lymphoma," Hasan and colleagues report that "it requires 738 prescriptions of dupilumab to produce one case of CTCL [cutaneous T-cell lymphoma]." It seems that this finding could easily be due to 1 in 738 people with a rash thought to be severe atopic dermatitis needing dupilumab having CTCL, not atopic dermatitis, to begin with. If we were to wonder whether dupilumab causes CTCL, perhaps it would be better to study asthma patients treated with or without dupilumab.