Clinical Age-Specific Seasonal Conjunctivitis Patterns and Their Online Detection in Twitter, Blog, Forum, and Comment Social Media Posts

Abstract

Purpose: We sought to determine whether big data from social media might reveal seasonal trends of conjunctivitis, most forms of which are nonreportable.

Methods: Social media posts (from Twitter, and from online forums and blogs) were classified by age and by conjunctivitis type (allergic or infectious) using Boolean and machine learning methods. Based on spline smoothing, we estimated the circular mean occurrence time (a measure of central tendency for occurrence) and the circular variance (a measure of uniformity of occurrence throughout the year, providing an index of seasonality). Clinical records from a large tertiary care provider were analyzed in a similar way for comparison.

Results: Social media posts machine-coded as being related to infectious conjunctivitis showed similar times of occurrence and degree of seasonality to clinical infectious cases, and likewise for machine-coded allergic conjunctivitis posts compared to clinical allergic cases. Allergic conjunctivitis showed a distinctively different seasonal pattern than infectious conjunctivitis, with a mean occurrence time later in the spring. Infectious conjunctivitis for children showed markedly greater seasonality than for adults, though the occurrence times were similar; no such difference for allergic conjunctivitis was seen.

Conclusions: Social media posts broadly track the seasonal occurrence of allergic and infectious conjunctivitis, and may be a useful supplement for epidemiologic monitoring.

Figure 1

Conversation topics, Twitter. Topic wheels created from a random sample of 1000 posts used for analysis. Left: younger. Right: older. Top: infectious. Bottom: allergic. Source: Crimson Hexagon.

Figure 2

Conversation topics, all ages. Left: infectious conjunctivitis. Right: allergic. Top: Twitter. Bottom: forums. Source: Crimson Hexagon.

Figure 3

Weekly EMR and social media counts and estimated seasonal pattern fitted curves: conjunctivitis groups and age groups for clinical and social media data. Weekly count data, using data from over a multiple years, were analyzed using negative binomial regression to create fitted seasonal curves. Panels show raw weekly data and corresponding fitted curves, these can be compared between conjunctivitis infectious, allergic and other groups for both EMR clinical data as well as analogous Twitter or Forum post conjunctivitis post groups. Rows: Clinical cases (row 1); Twitter (row 2); and forums (row 3). Columns: All ages combined (column 1); younger ages (column 2); older ages (column 3). Colors: fitted curves for infectious conjunctivitis (red); fitted curves for allergic conjunctivitis (green); observed weekly counts (gray). Each tick on the horizontal axis represents 6 months and each date listed corresponds to the tick mark centered above its listed date.

Figure 4

Smoothed detrended seasonal curves. (A) Infectious conjunctivitis for older (thick lines) and younger individuals (thin lines); clinical EMR (solid lines); and Twitter (dashed lines). (B) Allergic conjunctivitis for older (thick lines) and younger (thin lines); clinical EMR (solid lines); and Twitter (dashed lines). (C) Infectious conjunctivitis (red) and allergic conjunctivitis (green), for pediatrics (solid lines) and ophthalmology (dashed lines). (D) Clinical influenza (blue) and infectious conjunctivitis (red), for older (solid lines) and younger individuals (dashed lines). (E) Clinical influenza (blue); allergic conjunctivitis (green); infectious conjunctivitis (red); and corneal ulcers (gray), all ages. X-axis: top tick marks are 10-week intervals starting at week 0, bottom tick marks indicate middle of months.

Figure 5

Timing and degree of seasonality for selected clinical and social media data. The circular mean week of occurrence is shown on the horizontal axis; the vertical axis displays a measure of degree of seasonality (one minus the circular variance; higher location indicates greater seasonality). Infectious conjunctivitis is shown in red, allergic conjunctivitis in green. Glaucoma and corneal ulcers are shown for comparison.

Figure 6

Age-based and monthly UCSF EMR emergency medicine data, for comparison to national clinical emergency department data (see Ref. 32). Top: age distributions stratified by sex (for comparison, see figure 1a of Ref. 32). Center: age distributions stratified by conjunctivitis diagnosis code groups (for comparison, see figure 1b of Ref. 32). Bottom: monthly distributions stratified by conjunctivitis diagnosis code groups (for comparison, see figure 2b of Ref. 32).