Seasonal variations of Google searches for joint swelling: implications for patient-reported outcomes

Excerpt

Seasonal variation of symptoms and signs in rheumatic diseases are well recognised, whether it is due to sunlight for photosensitive rashes [1], temperature for Raynaud’s phenomenon [2], or less tested theories such as humidity or atmospheric pressure for arthralgia. A recent interrogation of Google search data suggested that gout attacks may follow seasonal patterns, peaking in the late spring/early summer [3]. Gout has characteristic clinical features that can make it a clinical spot-diagnosis, but individuals with an acute monoarthritis are far more likely to report to their doctor with (or search online for) “I have a painful, swollen toe”, rather than “I have gout” (although no doubt with the help of Google, this is increasingly common). While a lay impression or suspicion of gout may not be an acceptable definition to infer seasonality of gout incidence, Google search data for joint swelling—a symptom of many rheumatic diseases—is of major clinical significance. If patients’ self-report of joint swelling changes throughout the year, then many patient-reported outcomes may be impacted, for example, the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), which asks patients to self-report “the overall level of pain or swelling in joints other than neck, back, hips.” We therefore examined seasonal variations in joint swelling using Google search data. …