Results
Our search results yielded 263 groups on Facebook; 187 groups were eligible for data extraction and analysis after exclusion criteria were applied (Figure). A total of 8,966 Facebook users were members of these eligible groups related to hypertension, and the membership size of each group ranged from 1 to 2,161 individuals. Overall intercoder reliability in our study was 89.8%.
Table 1 shows the general characteristics of the Facebook groups included in the study. Group activities were restricted to a particular geographical location (country or region) for 15% of the groups as indicated by the title of these groups (eg, Singapore Hypertension Club, Pulmonary Hypertension Support Group for Southern Alberta, High Blood Pressure North Florida ), and the remaining 85% of the groups were considered global. By analyzing the main objective of each group we identified the following 7 major categories of hypertension groups by their group descriptions: a) awareness-creating groups ("Our goal is to make people aware about hypertension"), b) support groups for patients and caregivers ("This is a support group for people living with pulmonary arterial hypertension and their family and friends"), c) disease experience-sharing groups ("I am 27 and I have 3 beautiful kids and I am now living with severe idiopathic pulmonary hypertension. I need to know how some of you deal with knowing you are fighting for your life every single day and not break down"), d) fundraising groups ("This group is for those that wish to help us by offering donations or by volunteering yourself, your time, your talents for the organization"), e) product-promotion groups (selling online-generic Lopressor (metoprolol) at discount prices), f) research groups (High Blood Pressure Clinical Research Trial], g) health professional groups (Libyan Academy of Hypertension). Our analyses revealed that most (59.9%) of the Facebook groups were created mainly to promote hypertension awareness. Table 1 lists the key objectives of the Facebook groups and the number and percentage of groups with each objective.
Most (21.3%) of the top-displayed most recent wall posts focused on promoting a product or service related to hypertension. The themes of the Facebook groups' top-displayed most recent wall posts with respective proportions and percentages are illustrated in Table 2. Of the 187 groups analyzed, 27.8% had activity since January 1, 2013, and 72.2% groups had no activity since that date (Table 1). Stepwise logistic regression analyses showed that the level of activity of the hypertension-related Facebook groups was independently associated with group size (AOR, 1.02; 95% CI, 1.01–1.03), presence of at least 1 "like" on the most recent wall post (AOR, 3.55; 95% CI, 1.41–8.92), and presence of at least 1 attached file on the group wall (AOR, 5.01; 95% CI, 1.25–20.1). These associations should be interpreted with caution, because the variable "group-size" was not normally distributed and showed relatively small magnitude in CI, and the variable "presence of attached file" showed wide CI, possibly because of the small number of analyzed Facebook groups). Further studies with larger numbers may confirm our findings. Finally, the Hosmer–Lemeshow test indicated that the logistic regression model fitted the data in our study well (P = .24). Table 3 illustrates the association of selected characteristics with level of activity of the Facebook groups.