Protocol for a systematic review: association between airborne pollen, intermittent allergic rhinitis and blood pressure

Previous epidemiological studies have found an increased risk of cardiovascular morbidity and mortality following days with heightened pollen exposure and suggested that intermittent allergic rhinitis might be associated with blood pressure. Pollen sensitization and subsequent pollen exposure cause local inflammation and cytokine release in individuals with intermittent allergic rhinitis (pollen allergy). Inflammatory mediators can travel throughout the body, hence providing the physiologic basis by which pollen allergy may lead to systemic inflammation, which is known to be a risk factor for cardiovascular events. However, the findings regarding the potential association between intermittent allergic rhinitis, pollen exposure, and cardiovascular health are not fully conclusive. To date, no systematic review has been published on this topic. This systematic review seeks to answer: Are exposure to airborne pollen and intermittent allergic rhinitis associated with blood pressure? Secondary questions include: (1) Are there personal characteristics (sex, age) which modify a potential association between intermittent allergic rhinitis or pollen exposure with blood pressure and/or hypertension? (2) What research gaps exist in our understanding of how intermittent allergic rhinitis, pollen exposure, and cardiovascular health are interrelated? Published herein are: Protocol for the systematic review, including the search strategy Supplement 1: PROSPERO registration Supplement 2: Data extraction table Supplement 3: Risk of bias assessment strategy Supplement 4: Risk of bias assessment tool