Study: Psoriasis Not an Independent Risk Factor for COPD Development

Psoriasis is not an independent risk factor for chronic obstructive pulmonary disease (COPD) development, according to a study published in Respiratory Medicine.¹

Recent research suggested a relationship between psoriasis and pulmonary diseases.² Because psoriasis is a chronic inflammatory disease, and COPD is characterized by diffuse pulmonary inflammation, the researchers said it is “essential” to understand whether patients with psoriasis are at increased COPD development risk, which may result in worse health outcomes.³ Therefore, they aimed to compare COPD prevalence, incidence, and risk among US patients with psoriasis to those without psoriasis.¹

Psoriasis is not an independent risk factor for developing chronic obstructive pulmonary disease (COPD). | Image Credit: Daniel Beckemeier

To determine COPD prevalence among patients with psoriasis, the researchers obtained data from the National Health and Nutrition Examination Surveys (NHANES) database, a nationally representative survey that assesses the health status of the US population; more specifically, they collected psoriasis information in the 2003 to 2006 and 2009 to 2014 NHANES cycles. Based on recommendations from the National Center of Health Statistics, the researchers combined 2 NHANES cycles (2011-2012 and 2013-2014) to improve statistical reliability and prevalence estimate stability.⁴

The NHANES study population consisted of patients over 20 years old who provided “yes” or “no” answers to whether they have a physician-given psoriasis diagnosis;¹ it also consisted of those who provided “yes” or “no” answers to whether they have a physician-given diagnosis of COPD, chronic bronchitis, or emphysema. Also, the researchers included various covariates from the NHANES database, including patients’ sex, age, and race/ethnicity.

Also, to determine COPD incidence and risk in patients with psoriasis, the researchers obtained data from the Optum Clinformatics Data Mart (CDM), a deidentified database of administrative health claims from US members with Medicare Advantage and commercial insurance plans. From Optum CDM, the researchers included those 18 years or older with either a psoriasis diagnosis or no history of a psoriasis diagnosis.

They defined a psoriasis diagnosis as at least 2 visit dates associated with relevant International Classification of Diseases, Ninth Revision (ICD-9) or ICD, Tenth Revision (ICD-10) codes. Similarly, the researchers defined a COPD diagnosis as at least 1 visit associated with relevant ICD-9 or ICD-10 codes. However, they excluded those in the Optum CDM with less than 1 year of continuous enrollment from the study entry date to ensure the availability of adequate follow-up data.

Additionally, the researchers collected several covariates from Optum CDM, namely patients’ race, sex, and age. They also included clinical covaries, like tobacco use, asthma, and a history of an obese body mass index (BMI).

The researchers identified 7,029,160 weighted patients over 20 years old with psoriasis using the NHANES database. COPD was prevalent in 9.64% of patients with psoriasis (95% CI, 6.73-13.63). This was higher than the COPD prevalence among those without psoriasis, which was 6.94% (95% CI, 6.08-7.93).

To determine COPD incidence and risk among patients with psoriasis, they identified 481,076 patients with psoriasis and 43,624,233 psoriasis-free controls using Optum CDM. Among patients with psoriasis, there were 10.74 COPD cases per 1000 person-years. More specifically, those with a disease duration of less than 5 years had a higher COPD incidence (18.42 cases per 1000 person-years) than those with a disease incidence of 5 years or more (9.93 cases per 1000 person-years).

The researchers noted that the COPD prevalence among patients with psoriasis was higher than that of the psoriasis-free controls; in the control group, there were 6.36 COPD cases per 1000 person-years. However, after adjusting for sociodemographic and clinical covariates, psoriasis was not significantly associated with COPD development risk (HR, 0.99; 95% CI, 0.98-1.00; P = .271).

The researchers acknowledged their limitations, the main one being that the NHANES questionnaire only captures those who received a diagnosis of psoriasis from a health care professional. Consequently, the data may not capture those with undiagnosed psoriasis.

Lastly, they explained that the association between COPD and psoriasis is “greatly complicated” by the relationship of both conditions with tobacco smoking; smoking is an independent risk factor for both COPD and psoriasis development. Therefore, these relationships may explain why patients with psoriasis have an increased COPD prevalence and incidence than patients without psoriasis. However, isolating the effects of psoriasis from smoking showed that psoriasis alone is not significantly associated with COPD development.

“Overall, this suggests that the increased prevalence and incidence of COPD in psoriasis patients is likely due to the strong correlation between psoriasis, smoking, and COPD,” the authors wrote.

References

1. Guo L, Bilimoria SN, Kikuchi R, et al. Prevalence, incidence, and risk of chronic obstructive pulmonary disease among psoriasis patients. Respir Med. Published online July 2, 2024. doi:10.1016/j.rmed.2024.107729
2. Ungprasert P, Srivali N, Thongprayoon C. Association between psoriasis and chronic obstructive pulmonary disease: a systematic review and meta-analysis. J Dermatolog Treat. 2016;27(4):316-321. doi:10.3109/09546634.2015.1107180
3. Christenson SA, Smith BM, Bafadhel M, Putcha N. Chronic obstructive pulmonary disease. Lancet. 2022;399(10342):2227-2242. doi:10.1016/S0140-6736(22)00470-6
4. Johnson CL, Dohrmann SM, Burt VL, Mohadjer LK. National health and nutrition examination survey: sample design, 2011-2014. Vital Health Stat 2. 2014;(162):1-33.