Table 2.

Gambling consumption indices and harm measurement

Gambling consumption indices
Gambling frequency	Gambling frequency was assessed using the first item (GDITitem1) of the Gambling Behavior subscale: “How often do you gamble?“, with response options of “Never” (0), “Monthly or less” (1), “2–4 times a month” (2), “2–3 times a week” (3), “4 or more times a week” (4), “Daily” (5), “Several times a day” (6).
Gambling duration	Gambling duration was assessed using the gambling frequency item (GDITitem1) and the second item (GDITitem2) of the Gambling Behavior subscale: “How much time do you spend gambling on a typical day?“, with responses of “No time” (0), “Less than an hour” (1), “1–2 hours” (2), “3–4 hours” (3), “5–6 hours” (4), “7–9 hours” (5), and “10–24 hours” (6). Gambling duration was derived by first recoding GDITitem1 and GDITitem2 into frequencies per month, i.e., 0, 0.5, 1.5, 3.5, 5, 8 and 17 h, and 0, 1, ,3, 10, 16, 30 and 30 days, respectively. These recoded variables were then multiplied with each other.
Gambling expenditure/gambling expenditure as a proportion of income	Gambling expenditure was assessed using one item in the GDIT appendix “How much money did you wager last month on gambling?” (GDITwager item). The expenditure as a proportion of income was estimated by dividing the appendix items (GDITwager item) by “What was your income after tax last month (including salary and grants)?” (GDITincome item), multiplied by 100.
Gambling diversity	Gambling diversity was assessed in a checkbox grid in the GDIT appendix, specifying engagement in problematic gambling activities (Slots, Poker, Casino table games, Sports betting, Horse betting, Bingo, Lotteries, and Instant lotteries/Scratch cards), assessed online or at venues. These items were summarized into binary variables for access mode (any online or venue gambling, regardless of type), or specific activities (regardless of access mode).
Gambling harm	Gambling harm was measured using the Negative Consequences subscale, encompassing past-year gambling-related worsened mental health (GDITitem12), experiences of financial problems (GDITitem11), or relationship problems (GDITitem13), or work or school difficulties (GDITitem14). The past-year negative consequences/harms endorsed in GDITitems11−14 (excluding responses “Yes, but not in the past year”) were summarized into a numeric variable (1–4 harms). Analyses were then conducted using cut-offs of + 1 harms (to prioritize sensitivity) as well as + 2 harms (in line with most previous research on lower-risk gambling limits.
Problematic gambling types	The checklist in the GDIT appendix used to calculate gambling diversity was employed to measure problematic gambling types. These were dichotomized into a binary variable for each specific gambling type (collapsed online and venue gambling). For descriptive purposes, they were also dichotomized into a binary variable for online or venue gambling (collapsed specific gambling types).