Baseline characteristics
Overall 2500 paper-based questionnaires were successfully delivered and 1817 responses received (response rate of 72.7%).
1194 females (65.7%) and 623 males (34.3%) participated in our study. Age distibution was the following: 18-25 years 2.5% (46/1817), 26-35 years 11.9% (217/1817), 36-45 years 31.8 % (577/1817), 46-55 years 33.1% (602/1817), 56-62 years 15.7% (285/1817) and 5.0% above 62 (90/1817) (Table 1)
73.6% (1339/1817) were married or lived in a relationship, 26.4 % (478/1817) were single. 23.1% (419/1817) had no children, 22.8 % (414/1817) had one child, 38.9% (706/1817) had two and 15.2% (278/1817) had three or more chidren.
0.5% (9/1817) had elementary degree, 5.8% (105/1817) had secondary education and 93.7% (1703/1817) had university graduation.
2.9% (54/1817) have been employed for less than a year. 37.0% (671/1817) of the study population have been working between 21-40 years, 32.1% (584/1817) have been working between 11-20 years and 2.2% (40/1817) more than 40 years. 12.8% (233/1817) had also a secondary employment (Table 1).
Risk factors and previous diseases
15.1% (275/1817) were regular smokers, 5.1 % (93/1817) were taking alcohol and 2.9% (52/1817) were taking illicit drugs more or less regularly.
22.8% (414/1817) had hypertension, 7.4 % (135/1817) were diabetic, 10.2 % had ischemic heart disease (186/1817), 8.0% (146/1817) suffered from musculoskeltal pain, and 1.5% (27/1817) had a history of depression (Table 2).
Duration and goal of internet use
38.3% (696/1817) spent less than one hour online and 2.0% (35/1817) used the internet more than six hours a day. More than half of the examinded workers preferred being online between 6-9 pm (51.9%, 943/1817). The main goals of internet surfing were to every day work 93.0% (1689/1817), visit community portals 42.5% (773/1817) and listening to music in 30.0% (539/1817). Detailed data can be seen in Table 2.
Internet addiction
Internet addiction was detected in 5.2% (95/1817) based on the Problematic Internet Use Quetionnaire. Internet addiction was more common in males (62.1 vs 32.7%, p=0.001) and workers below 35 years of age (29.5 vs. 13.6 %, p < 0.001). Being middle-aged or older was protective against IA (54.8 vs. 34.7 %, p =0.001, mostly driven by aged between 45-55)
IA was more prevalent among singles (23.1 vs 14%%, p=0.011), and childless (34.7 vs 22.4 %, p=0.004) (Table 3). Living in a relationship (74.2 vs 63.1%, p=0.018, mostly driven by being married) or having at least two children (55 vs 40%, p=0.004, mostly driven by having two children) were protective against IA.
Lower educational level was also associated with IA (3.2 vs 0.3%, p<0.001).
Working for less than a year was a predictor of IA (7.3 vs 2.7%, p=0.009), while working for > 20 years was protective (40.1 vs 21.1%, p<0.001) (Table 3). Having a secondary employment was significantly associated with problematic internet use (85.3 vs 12.7%, p<0.001)
There was a significans assoction between the duration of being online and being addicted to internet (r=0.36, p<0.001) (Table 4). The cut-off of spending 5 hours or more online predicted IA. We have found no association between daily time interval of internet use and IA.
Among the types of internet services internet gaming (25.2 vs 7.8%), chatting 4(0 vs 21.6%) and matchmaking (11.6 vs 2.4%, p<0.001 in all cases) were significantly associated with IA (Table 4).
Internet addiction was more prevalent among smokers (34.7 vs 14.1%), alkohol and drug users (17.9% vs. 4,4%, 15.8% vs 2.1%, p<0.001 in all cases). Diabetes (13.7 vs 7.1%, p=0.016) and history of depression (8.4 vs 1.1%, p<0.001) were significantly associated with problematic internet use (Table 4).
In a multivariate analysis including of all factors (demographic data, internet habits, comorbidity etc) age < 35 years (OR: 6.098, CI: 5.09-7.08, p<0.001), male gender (OR=5.413, CI: 4.39-6.18, p=0.002), surfing on the internet > 5 hours daily (OR 2.568, CI: 2.03-3.39, p<0.001), having no children (OR: 1.353, CI: 1.13-1.99, p=0.0248), and having secondary employment (OR=11.377, CI: 8.67-13.07, p=0.001) were significantly associated with internet addiction.