Assessment of video game addiction often involves measurement of peripheral criteria that indicate high engagement with games, and core criteria that indicate problematic use of games.
An implication of using only the core criteria is that the estimated prevalence of addiction will be slightly higher because endorsement of the peripheral criteria is not considered.
When the ASAS peripheral criteria were applied, 161 patients met these criteria (13 with isolated pSpA and 148 with a combined ax/p pattern).
While the latent variable "engagement" can be measured by items that tap peripheral criteria, the latent variable "addiction" can be measured using items that tap the core addiction criteria.
This fluctuation was dependent on the application to our patients of either the axial or peripheral criteria (table 1), these two sets of ASAS criteria being simultaneously met in 137 patients.
In the two-dimensional structure, items 1 3 of the GAS were determined to load on one factor, named "peripheral criteria," and items 4 7 were determined to load on the other factor, named "core criteria" (see Table 1).
It is remarkable that in our study, 100% of the patients positive for HLA-B15 met with the ASAS peripheral criteria and 100% of the HLA-B27 positives fulfilled the ASAS axial criteria.
One recent study used the GAS to categorize respondents as highly engaged gamers (those who endorsed all three peripheral criteria but no more than one of the core criteria), problem gamers (those who endorsed two or three of the core criteria), addicted gamers (those who endorsed all four core criteria), or non-problem/non-engaged gamers (all others).
Using the CORE 4 approach, endorsement of all four core addiction criteria is needed to categorize someone as an addicted gamer, whereas with the GAS 7 approach, all three peripheral criteria must also be endorsed in order to be categorized as an addicted gamer.
Confirmatory factor analysis showed that a two-factor structure, which separated peripheral criteria from core criteria, fitted the data better (CFI=0.963; RMSEA=0.058) compared to the original one-factor solution where all items are determined to load only on one factor (CFI=0.905, RMSEA=0.089).
