Dependency on Smartphone Use and Its Association with Anxiety in Korea

Transcription

1 Reserch Dependency on Smrtphone Use nd Its Assocition with Anxiety in Kore Kyung Eun Lee, MD Si-Heon Kim, MD Te-Yng H, MD Young-Myong Yoo, MD Ji-Jun Hn, MD Je-Hyuk Jung, MD Je-Yeon Jng, PhD ABSTRACT Objective. South Kore hs the highest rte of smrtphone ownership worldwide, which is potentil concern given tht smrtphone dependency my hve deleterious effects on helth. We investigted the reltionship between smrtphone dependency nd nxiety. Methods. Prticipnts included 1,236 smrtphone-using students (725 men nd 511 women) from six universities in Suwon, South Kore. Prticipnts completed mesures of smrtphone use, smrtphone dependency, nxiety, nd generl chrcteristics (i.e., demogrphic, helth-relted, nd socioeconomic chrcteristics). To mesure smrtphone dependency nd nxiety, we used questionnires of Yng s test developed from Young s Internet Addiction Test nd Zung s Self-Rting Anxiety Scle. We used multiple logistic regression to determine the ssocition between smrtphone dependency nd nxiety fter djusting for relevnt fctors. Results. On scle from 25 to 100, with higher scores on the smrtphone dependency test indicting greter dependency, women were significntly more dependent on smrtphones thn were men (men smrtphone dependency score: 50.7 vs for men nd women, respectively, p). However, the mount of time spent using smrtphones nd the purpose of smrtphone use ffected smrtphone dependency in both men nd women. Prticulrly, when dily use time incresed, smrtphone dependency showed n incresing trend. Compred with times of use,2 hours vs. $6 hours, men scored 46.2 nd 56.0 on the smrtphone dependency test, while women scored 48.0 nd 60.4, respectively (p). Finlly, for both men nd women, increses in smrtphone dependency were ssocited with incresed nxiety scores. With ech one-point increse in smrtphone dependency score, the risk of bnorml nxiety in men nd women incresed by 10.1% nd 9.2%, respectively (p). Conclusion. Among this group of university students in South Kore, smrtphone dependency ppered to be ssocited with incresed nxiety. Stndrds for smrtphone use might help prevent deleterious helth effects. Ajou University School of Medicine, Deprtment of Preventive Medicine nd Public Helth, Suwon, Republic of Kore Address correspondence to: Je-Yeon Jng, PhD, Ajou University School of Medicine, Deprtment of Preventive Medicine nd Public Helth, 164 Worldcup-ro, Yeongtong-Gu, Suwon, Gyeonggi-do, 16499, Republic of Kore; tel ; fx ; e-mil <free5293@gmil.com> Assocition of Schools nd Progrms of Public Helth 411

2 412 Reserch Smrtphones (mobile telephones tht run on portble operting systems) re more dvnced thn regulr mobile telephones becuse they hve dvnced cpbilities, such s wireless Internet ccess. 1 Smrtphone sles hve incresed rpidly worldwide, with n estimted 300 million smrtphones being purchsed nnully fter ,3 South Kore hs the highest rte of smrtphone ownership worldwide, with 58% of dults nd 84% of college students reportedly using smrtphones in Moreover, the number of smrtphone users continues to increse. 4,5 Becuse smrtphones fford greter ccess to medi, their use my led to unexpected helth problems, such s Internet ddiction. 6,7 Although ddiction is considered to be pthologic condition chrcterized by persistent use nd excessive dependency, 8 studies on the helth effects of smrtphone use (e.g., psychologicl effects, smrtphone dependency risk) re scrce. Hwng et l. found positive correltion between smrtphone overuse nd upper extremity pin, while severl cse reports nd studies noted incresed ddictive nd depressive symptoms s function of smrtphone use Im et l. reported positive correltions of smrtphone ddiction level with scores mesuring psychotic depression nd obsessive-compulsive disorder. 11 However, most studies were limited in their smpling techniques (e.g., smll smple sizes, convenience smples) 7,11,13 or did not control for confounding fctors. Assessing compulsive nd dependent symptoms s confounding fctors would help ddress the effects of potentil comorbidities on smrtphone ddiction. 10,14 Given tht smrtphones re portble, provide convenient Internet ccess, nd hve functions tht llow for multitsking, they could promote dependence to greter degree thn regulr mobile telephones or Internet ccessed from computer. 1,15 Incresed smrtphone dependency is puttive risk fctor for industril injuries or utomobile ccidents (vi disrupted concentrtion), musculr pin, nd nxiety. 7,9,15 Incresed use of smrtphones lso reltes to mentl helth problems, such s incresing depression nd nxiety. 5,10,11 Anxiety disorders, which re mong the most prevlent mentl disorders, my be prticulrly excerbted by smrtphone use becuse they re relted to substnce ddiction nd dependency. 16,17 Notbly, the reltionship between smrtphone overuse nd negtive psychologicl dpttion is moderted by demogrphic chrcteristics, smrtphone use preferences, nd inpproprite use However, reserch studies identifying the helth effects from smrtphone overuse considering those fctors re rre. Apprent differences by sex exist in the perceptions of socil contct, motivtion for technology use, nd compulsive use of medi nd substnces. 19,21 For exmple, men re t greter risk for ddiction to lcohol, smoking, nd computer gmes, wheres 19,22,23 women re more likely to immerse themselves in online socil networking. 1,21 Hwng et l. reported tht men s smrtphone use ws driven by the desire to show off new technologies nd entertinment medi, while women s smrtphone use ws motivted by the desire to communicte. 14 Thus, sex my ffect smrtphone dependency. 20,24 We exmined helth-relted, demogrphic, nd socioeconomic fctors s potentil influences on smrtphone dependency. Additionlly, we investigted the reltionship between smrtphone dependency nd nxiety by sex. METHODS Prticipnts Prticipnts were students in lrge, open-lecture clssrooms of six universities locted in Suwon, South Kore, recruited vi cluster smpling. First, we selected ll universities (four institutions with four-yer curriculums nd two institutions with two-yer curriculums) in Suwon nd investigted summer lecture schedules. Then, we selected clsses in ech university in which the registrtion ws not limited by mjor or grde. Of the 1,296 open-lecture students, totl of 1,261 (97.3%) consented to prticipte. The survey ws conducted in July nd August 2013 vi closedended questionnire. Five trined investigtors visited clsses in six universities nd performed fce-to-fce interviews for nxiety nd smrtphone dependency. Prticipnts self-reported demogrphic chrcteristics nd behviorl chrcteristics on smrtphone use in questionnires. Dt collected from reserchers nd prticipnts were electroniclly entered nd checked for ccurcy by reserch stff members. Dt collection instruments nd vribles The survey ssessed smrtphone use ptterns (including totl use time), situtions in which smrtphones re frequently used, verge dily use (in hours), nd purpose of use. Situtions were described s ctivities they frequently perform while using smrtphones, such s commuting or trveling, trnsporttion or wlking, working or ttending lecture, nd before sleeping. We included the ctivity of spending brek time using mobile telephones for prticipnts who use their smrtphones during brek time or do nothing else when using their smrtphones. We defined smrtphone dependency s persistent smrtphone use despite problems relted to tht use. We mesured

3 Smrtphone Use nd Anxiety in Kore 413 smrtphone dependency using Yng s questionnire on mobile telephone dependency, which ws bsed on Young s Internet Addiction Test. 25,26 We modified the items in Yng s questionnire to ssess smrtphone dependency. The questionnire hs estblished vlidity 15,25 28 nd comprises 25 items in four subscles (obsession, withdrwl, relince, nd disturbnces in dily life). Obsession indictes persistent use of smrtphones (e.g., How often do you use smrtphone longer thn you intended? ). Withdrwl indictes experiencing nervous symptoms or repetitive illusions of ringing when not using smrtphone. Relince, chrcterized s excessive psychologicl ttchment, indictes ttching gret importnce to smrtphones. We mesured relince in terms of the frequency of experiencing deep sense of loss when unble to use smrtphones (e.g., How often do you fer tht life without your smrtphone would be boring, empty, nd joyless? ). Disturbnces in dily life indictes significnt distress nd impirment of socil, occuptionl, nd role functioning due to excessive use of smrtphones. We mesured disturbnces in dily life with questions such s, How often do you lose sleep due to lte-night use of smrtphone? (Tble 1). Totl scores rnged from 25 to 100, with higher scores indicting greter smrtphone dependency. Cronbch s for the totl score in the present study ws 0.90 (rnge: for the subscles in previous studies), 26,28 which is considered relible. We ssessed nxiety, defined s uncontrollbly excessive nd persistent worrying tht cuses excerbted distress, with n dpted version of Zung s Self-Rting Anxiety Scle. This scle comprises 20 items in four subscles. Totl scores rnge from 20 to 80, with norml level of nxiety defined s #44. Cronbch s for the scle ws We ssessed demogrphic, socioeconomic, nd helth-relted chrcteristics, including sex, ge, economic sttus, cdemic chievement, self-rted helth, smoking ptterns, mount of lcohol consumed, presence of physicl or mentl illness, nd fmily history of mentl illness. For smoking ptterns, prticipnts reported whether or not they hd smoked during the Tble 1. Questionnire ssessing problemtic use of mobile telephones by Yng for study of smrtphone use mong students t six universities in Suwon, South Kore, July August 2013 Subscle Obsession Withdrwl Relince Disturbnces in dily life Questions bout mobile telephone use How often do you use your mobile telephone longer thn you intended? How often do others in your life complin to you bout your excessive mobile telephone use? How often do you find yourself sying just few more minutes when using your mobile telephone? How often do you try to cut down the mount of time you use your mobile telephone but fil? How often do you feel tht you cnnot help buying yourself new mobile telephone whenever new model is lunched? How often do you prefer the excitement of mobile telephone use to intimcy with prtner or friends? How often do you check your mobile telephone before something else tht you need to do? How often re you nervous bout missing cll or messge when you cnnot use mobile telephone? How often do you snp, yell, or ct nnoyed if someone bothers you while you use mobile telephone? How often do you think tht your mobile telephone is ringing even when you do not hve it? How often do you use mobile telephone during school hours? How often do you think tht spending time with your mobile telephone is the most enjoyble wy to spend time? How often do you feel nervous when you re not llowed to use your mobile telephone? How often do you spend time with your mobile telephone to void troublesome tsks? How often do you feel tht life without your mobile telephone would be boring, empty, nd joyless? How often do you feel depressed, moody, or nervous when you cnnot use your mobile telephone, which goes wy once you cn use it? How often do you find yourself nticipting when you will use your mobile telephone gin? How often do you think using your mobile telephone is the most importnt ctivity in your dily schedule? How often do you block out disturbing thoughts bout your life with soothing thoughts of your mobile telephone? How often do you neglect household chores to spend time using your mobile telephone? How often do your fmily nd friends complin bout the mount of time you use your mobile telephone? How often do your grdes or schoolwork suffer becuse of the mount of time you use your mobile telephone? How often do you find yourself using your mobile telephone unconsciously? How often do you hve lck of concentrtion while studying due to mobile telephone use? How often do you lose sleep due to lte-night use of your mobile telephone? Scoring on ech item ws 1 to 4 bsed on prticipnts nswers, with 1 5 rrely, 2 5 occsionlly, 3 5 often, nd 4 5 lwys. Totl scores rnged from 25 to 100, with higher scores indicting greter smrtphone dependency. Adpted with permission from: Yng SY. Studies for mobile phone ddiction in high school students. Sejong-si (South Kore): Kore Ntionl Youth Policy Institute; 2002.

4 414 Reserch pst six months; for lcohol consumption, prticipnts rted the number of times they hd consumed lcohol in the pst month (i.e.,.60 grms of pure lcohol ech time for men,.40 grms of pure lcohol ech time for women). Those who consumed lcohol more thn once per week were clssified s high risk. We lso collected dt on physicl nd mentl illness dignoses (including nxiety) during the pst three yers. Physicl illnesses (e.g., rrhythmi nd thyroid disese) included those ssessed by Flint 30 nd mentl illnesses (e.g., depression, schizophreni, nd bipolr disorder) includes those ssessed by Alloy et l. 31 Sttisticl nlysis We strtified ll dt by sex nd excluded missing vlues from the nlysis. We used the Mnn-Whitney U-test nd Person s χ 2 test to compre smrtphone dependency scores by prticipnts chrcteristics nd smrtphone use ptterns. We used nlysis of covrince to compre smrtphone dependency scores by sex while controlling for generl chrcteristics nd smrtphone use ptterns. Finlly, we computed the ssocition between smrtphone dependency nd incidence of nxiety using odds rtios (ORs) vi multiple logistic regression. We used SPSS version 19.0 for ll nlyses. 32 RESULTS Of the 1,261 prticipnts, 15 (1.2%) did not use smrtphones nd 10 (0.8%) did not nswer ll of the questions; s such, their dt were excluded. Thus, the finl smple comprised 1,236 prticipnts (725 men nd 511 women). Prticipnts men ge differed significntly (p) between men (23.6 yers) nd women (21.5 yers). Additionlly, compred with women, men reported significntly higher rtes of smoking (38.8% vs. 27.8%) nd high-risk lcohol consumption (28.4% vs. 6.7%) (p). Compred with men, women reported significntly worse subjective helth (p) nd higher prevlence rtes of physicl illness (31.6% vs. 22.8%, p50.001) nd fmily history of mentl illness (6.5% vs. 3.4%, p50.019). The rte of bnorml nxiety, which ws.44 ccording to Zung s scle, ws reported by 20.1% of women nd 8.9% of men (p) (Tble 2). Smrtphone use ptterns differed by sex. More women thn men reported owning smrtphone for more thn two yers (61.6% vs. 46.3%, p) nd using smrtphone in bed before sleeping (33.7% vs. 24.3%, p). We found significnt difference by sex in usge situtions: 40.7% of women nd 24.8% of men reported using smrtphones frequently during brek time, 31.5% of men nd 37.2% of women reported using smrtphones frequently while commuting or trveling between plces, nd 3.5% of men nd 4.3% of women reported using smrtphones frequently during work or clss (p) (Tble 3). We lso found significnt differences by sex in verge dily smrtphone use (p). Twice the percentge of women s men (22.9% vs. 10.8%) used smrtphones for $6 hours per dy, greter percentge of women thn men used their smrtphones for 4,6 hours per dy (31.1% vs. 18.6%), nd greter percentge of men thn women used their smrtphones for,2 hours per dy (29.2% vs. 12.5%) (Tble 3). The purpose of smrtphone use differed by sex (p). The most common purpose of smrtphone use ws socil networking services for both men nd women, but women reported using socil networking services more frequently thn did men (51.7% vs. 39.2%). After socil networking services, the next most frequent use of smrtphones by men nd women ws to serch the Internet (20.5% of women nd 23.7% of men) nd for entertinment (18.2% of women nd 23.9% of men). Overll, women were significntly more dependent on smrtphones thn were men (men dependency score: 56.0 vs. 50.8, p) (Tble 3). Men nd women lso differed significntly when we exmined smrtphone dependency score by verge dily use time nd purpose of smrtphone use, with higher scores on scle from 25 to 100 indicting greter smrtphone dependency. For,2 hours, $2,4 hours, $4,6 hours, nd $6 hours of dily use time, men scored 46.2, 51.4, 53.4, nd 56.0, respectively, while women scored 48.0, 54.8, 57.3, nd 60.4, respectively (p). Thus, smrtphone dependency showed n incresing trend s dily use time incresed (Tble 4). Those who most frequently used their smrtphones for entertinment, serching the Internet, nd socil networking services hd significntly greter smrtphone dependency thn did those who most frequently used their smrtphones for clling/miscellneous functions (p). With ech one-point increse in smrtphone dependency score, the odds of hving bnorml nxiety in men nd women incresed by 10.6% nd 9.2%, respectively (p) (Tble 5). After djusting for known risk fctors for nxiety disorders (e.g., ge, helth, presence of physicl nd mentl illness, nd economic sttus), the odds of hving bnorml nxiety in men nd women incresed by 7% nd 9%, respectively (p), for every one-point increse in smrtphone dependency score.

5 Smrtphone Use nd Anxiety in Kore 415 Tble 2. Demogrphic chrcteristics nd nxiety scores, by sex, of students who use smrtphones t six universities, Suwon, South Kore, July August 2013 Chrcteristic Number of mle students (percent) Number of femle students (percent) P-vlue b Totl 725 (100.0) 511 (100.0) Age in yers: men (SD) 23.6 (2.7) 21.5 (2.7) Economic sttus c High income 207 (28.6) 130 (25.5) Middle income 375 (51.7) 287 (56.1) Low income 143 (19.7) 94 (18.4) Acdemic chievement c High grdes 223 (30.7) 139 (27.2) Middle grdes 294 (40.6) 217 (42.5) Low grdes 208 (28.7) 155 (30.3) Helth sttus c Excellent or good 459 (63.3) 238 (46.6) Fir 199 (27.4) 209 (40.9) Poor 67 (9.2) 64 (12.5) Drinking pttern d.1 time per week 206 (28.4) 34 (6.7) #1 time per week 519 (71.6) 477 (93.3) Cigrette smoking Smoker e 281 (38.8) 142 (27.8) Nonsmoker 444 (61.2) 369 (72.2) Physicl illness c 165 (22.8) 161 (31.6) Mentl illness f 36 (5.0) 18 (3.5) Fmily history of mentl illness f 25 (3.4) 33 (6.5) Anxiety score g Norml (#44) 660 (91.1) 408 (79.9) Anxiety (.44) 65 (8.9) 103 (20.1) Percentges my not totl to 100 becuse of rounding. b Mnn Whitney U-test nd Person s χ 2 test c Self-reports were recorded for economic sttus, cdemic chievement, helth sttus, nd physicl illness. The levels of high, middle, nd low income were determined by prticipnts subjective opinion of their reltive stte compred with their surroundings. d Averge lcohol consumption in the pst month (.60 grms of pure lcohol ech time for men nd.40 grms of pure lcohol ech time for women) e Prticipnts who reported tht they hd smoked during the pst six months f Mentl illnesses were bsed on self-report of dignosed illness from doctor within the pst two yers. g Totl scores rnge from 20 to 80, with norml level of nxiety defined s #44. Adpted from: Zung WW. A rting instrument for nxiety disorders. Psychosomtics 1971;12: SD 5 stndrd devition DISCUSSION Women hd higher smrtphone dependency scores thn men, suggesting tht women might be more vulnerble to smrtphone ddiction. This finding supports previous reserch. For exmple, Kim et l. noted tht the risk of mobile telephone ddiction my be higher in femle dolescents thn in mle dolescents becuse femles regrd interpersonl interction more highly. 33 Recently, mobile telephones hve come to be perceived s medium for interpersonl interction nd quick communiction, which my explin why women tend to use their smrtphones for longer periods of time. 21,33 Considering tht smrtphones hve strengthened interpersonl interction by online ccess (e.g., socil networking), ccording to study by Kim et l., the risk of smrtphone ddiction in women my be higher thn the increse in mobile telephone ddiction. 1 Averge dily use time nd purpose of smrtphone use lso ccounted for significnt differences in smrtphone dependency nd differences by sex. More thn hlf of ll smpled women, compred with one-third of men, used smrtphones for.4 hours per dy. Furthermore, more thn twice the percentge of women s men used their smrtphones for $6 hours per dy. Notbly, Young explined tht the more individuls experience sense of immersion in the Internet, the more they will become further immersed. 27 Thus, continuous, excessive Internet use cn led to dependence.

6 416 Reserch It is possible tht the sme principle pplies to smrtphone use. Nmely, women who re dependent on smrtphones my use their smrtphones for longer periods of time, which my, in turn, increse their dependence on smrtphones. However, further study is needed to provide evidence for this explntion. Regrding purpose of use, smrtphone dependency ws higher mong prticipnts who used smrtphones for socil networking services, Internet serches, nd medi-bsed entertinment thn mong prticipnts who used smrtphones for mobile telephone-relted functions. For exmple, both mle nd femle socil networking services users hd high smrtphone dependency scores; however, 51.7% of women, compred with 39.2% of men, were socil networking services users. Socil networking services use might hve led to women hving higher dependency scores thn men. Specificlly, more women ppered to believe tht interpersonl reltionships cn be fostered vi the Internet, which is consistent with women s preferences for socil networking services. 34 Additionlly, women tend to believe tht medi re useful in the development nd mintennce of reltionships, which coincides with their greter medi use. 35 For exmple, in longitudinl study of Jpnese texting behvior, women communicted with more people using text messges thn did men. 1 Furthermore, compred with men, women used smrtphones to communicte with others more often, which my contribute to greter smrtphone dependency mong women. Although not shown in the tbles, the interction between women s preferences for socil networking services nd totl smrtphone use ws not significnt. However, smrtphone dependency scores differed significntly by verge dily use nd purpose of use; thus, the min purpose of smrtphone use nd verge dily use my independently ffect smrtphone dependency. Smrtphone dependency scores were lso high mong students who minly used smrtphones entertinment functions compred with students using smrtphones s conventionl mobile telephones. This result coincides with previous results showing tht mobile telephone ddiction ws highly ssocited with entertinment-bsed use. 36 Additionlly, Prk nd Shin Tble 3. Smrtphone use ptterns nd men smrtphone dependency scores, by sex, of students t six universities, Suwon, South Kore, July August 2013 Smrtphone use ptterns Number of mle students (percent) Number of femle students (percent) P-vlue Totl 725 (100.0) 511 (100.0) Totl length of smrtphone ownership,6 months 50 (6.9) 20 (3.9) $6,12 months 91 (12.5) 31 (6.1) $1,2 yers 248 (34.3) 145 (28.4) $2 yers 336 (46.3) 315 (61.6) Situtions in which smrtphone is frequently used b Commuting or trveling between plces 229 (31.5) 190 (37.2) Working or ttending lecture 25 (3.5) 22 (4.3) During brek 295 (40.7) 127 (24.8) Before or while in bed 176 (24.3) 172 (33.7) Averge dily use time, in hours,2 212 (29.2) 64 (12.5) $2,4 300 (41.4) 171 (33.5) $4,6 135 (18.6) 159 (31.1) $6 78 (10.8) 117 (22.9) Purpose of use b Clling/miscellneous functions 96 (13.2) 49 (9.6) Socil networking services 284 (39.2) 264 (51.7) Serching/reserching the Internet 172 (23.7) 105 (20.5) Entertinment c 173 (23.9) 93 (18.2) Men smrtphone dependency score (SD) d 50.8 (10.2) 56.0 (10.4) Sex differences were compred using Mnn-Whitney s U-test in dependency score nd Person s chi-squred test in smrtphone use ptterns. b Respondents were sked to choose only one nswer tht most pplied to themselves from the list in ech question. c Medi-bsed entertinment functions includes digitl multimedi brodcsting, MP3, video plyer, cmer, nd gmes. d Totl scores rnged from 25 to 100, with higher scores indicting greter smrtphone dependency. Adpted from: Yng SY. Studies for mobile phone ddiction in high school students. Sejong-si (Kore): Kore Ntionl Youth Policy Institute; SD 5 stndrd devition

7 Tble 4. Smrtphone dependency scores, by sex, ccording to use ptterns of students t six universitie, Suwon, South Kore, July August 2013 Mle students Femle students Smrtphone dependency score Adjusted smrtphone Smrtphone dependency score b dependency score Adjusted smrtphone dependency score b Smrtphone use ptterns Men (95% CI) P-vlue c Men (95% CI) P-vlue c Men (95% CI) P-vlue c Men (95% CI) P-vlue c Totl length of smrtphone ownership,6 months 51.4 (48.6, 54.3) (48.0, 53.7) (53.3, 62.2) (50.7, 59.4) $6,12 months 50.4 (48.3, 52.5) 50.8 (48.7, 52.9) 55.4 (51.8, 59.0) 55.9 (52.5, 59.4) $1,2 yers 49.7 (48.4, 51.0) 50.2 (48.6, 51.7) 55.0 (53.3, 56.6) 54.5 (52.6, 56.4) $2 yers 51.5 (50.4, 52.6) 51.8 (50.4, 53.1) 56.4 (55.3, 57.6) 55.9 (54.4, 57.4) Situtions in which smrtphones is frequently used Commuting or trveling between plces 50.2 (48.9, 51.5) (49.0, 52.0) (45.7, 50.3) (51.4, 55.3) Working or ttending lecture 53.1 (49.1, 57.1) 51.0 (47.2, 54.8) 61.2 (57.0, 65.4) 58.1 (54.0, 62.2) During brek 50.6 (49.4, 51.8) 50.7 (47.2, 54.8) 55.5 (53.7, 57.2) 54.9 (52.8, 57.1) Before or while in bed 51.4 (49.9, 52.9) 51.4 (49.8, 53.0) 57.3 (55.8, 58.8) 55.0 (53.0, 57.0) Averge dily use time (in hours), (44.9, 47.5) 45.7 (44.0, 47.4) 48.0 (45.7, 50.3) 49.3 (46.4, 52.2) $2, (50.3, 52.5) 50.4 (48.9, 52.0) 54.8 (53.4, 56.3) 55.1 (53.0, 57.2) $4, (51.8, 55.1) 52.3 (50.3, 54.3) 57.3 (55.8, 58.8) 57.2 (55.0, 59.3) $ (53.8, 58.2) 55.1 (52.9, 57.3) 60.4 (58.7, 62.2) 59.9 (57.6, 62.1) Purpose of use Clling/miscellneous functions 45.6 (43.5, 47.6) 47.0 (44.0, 47.4) 50.6 (47.8, 53.4) 51.6 (48.6, 54.7) Socil networking services 52.2 (51.0, 53.3) 52.8 (51.2, 54.3) 57.0 (55.8, 58.2) 56.8 (55.0, 58.6) Serching/reserching the Internet 51.5 (50.0, 53.0) 52.7 (50.9, 54.4) 55.5 (53.5, 57.4) 56.1 (53.7, 58.5) Entertinment d 50.5 (49.0, 52.0) 51.1 (49,3, 52.8) 56.7 (54.7, 58.7) 56.8 (54.4, 59.2) Totl scores rnged from 25 to 100, with higher scores indicting greter smrtphone dependency. Adpted from: Yng SY. Studies for mobile phone ddiction in high school students. Sejong-si (Kore): Kore Ntionl Youth Policy Institute; b All vribles of behviorl ptterns of smrtphone use nd other vribles tht contributed to significnt differences in dependency (e.g., cdemic chievement in men nd cdemic chievement nd lcohol consumption in women) were djusted. c An nlysis of covrince ws used to compre the men of smrtphone dependency scores between groups of use ptterns. e Medi-bsed entertinment function including digitl medi brodcsting, MP3, video plyer, cmer, nd gmes CI 5 confidence intervl

8 418 Reserch Tble 5. Assocition between smrtphone dependency score nd nxiety score, by sex, in students t six universities, Suwon, South Kore, July August 2013 Mle students Femle students Dependency score OR (95% CI) P-vlue OR (95% CI) P-vlue Undjusted model 1.11 (1.08, 1.15) 1.09 (1.06, 1.12) Adjusted model b 1.07 (1.04, 1.11) 1.09 (1.06, 1.12) Totl scores rnged from 20 to 80, with norml level of nxiety defined s #44. Adpted from: Zung WW. A rting instrument for nxiety disorders. Psychosomtics 1971;12: b Using multiple logistic regression djusting for known risk fctors (i.e., ge, helth sttus, physicl nd mentl illness, nd economic sttus) OR 5 odds rtio CI 5 confidence intervl noted tht smrtphone dependency incresed when users need for fun ws stisfied vi plying gmes or wtching videos with the device. 8 The fct tht smrtphone dependency incresed by plying gmes cn be prtilly explined s n effect of video gme ddiction. According to study of Hong Kong dolescents, video gme ddiction ws significntly higher mong those who preferred multiplyer online gmes thn mong those who preferred other gmes. Wng et l. ssumed tht multiplyer online gmes incresed enjoyment nd interction with other plyers, which might result in prolonged gming sessions. 37 Becuse the smrtphone is optimized for portble online ccess, people who use it to ply gmes could end up using it more persistently. Thus, our results my show positive correltion between Internet nd video gme ddiction, lthough it should be directly confirmed in future studies. Men nd women lso differed by situtions in which they used smrtphones. Although men used smrtphones frequently when resting, women used them frequently when commuting or trveling or just before sleeping. Smrtphone dependency did not differ significntly by usge sitution mong men, but dependency scores were significntly higher mong women who used smrtphones during work or just before sleeping. However, the increse in dependency scores ws non-significnt fter controlling for smrtphone use nd confounding vribles. Importntly, smrtphone dependency ws significntly relted to nxiety, the most prevlent mentl disese, in both men nd women; this finding suggests tht dependency is not hbit but, rther, potentil public helth issue for smrtphone use. When the smrtphone dependency score incresed by one point, the odds of hving nxiety rose by 7% in men nd 9% in women fter djusting for nxiety disorder risk fctors. This finding supports work by Yun et l., 10 who reported tht 62.6% of smrtphoneddicted users complined of nxiety. 13 University students in Turkey demonstrted incresed nxiety mong hevy users of smrtphones, which the reserchers proposed ws medited by sleep disturbnces. 38 Furthermore, Hwng et l. reserched the reltionship between psychologicl chrcteristics nd mobile telephone ddiction mong femle university students nd found tht socil extrversion nd nxiety positively influenced ddiction. 14 Limittions This study ws subject to severl limittions. First, becuse the study ws cross-sectionl, cusl reltionships between smrtphone dependency nd nxiety could not be inferred. Second, the smple ws limited to Suwon nd specific ge group. As such, the results re not necessrily representtive of Kore becuse socioeconomic sttus nd environmentl conditions ffecting smrtphone use (e.g., popultion growth rte nd socil infrstructure for ccessing the Internet) differ mong regions. CONCLUSION Our study identified significnt differences in smrtphone use nd dependency for severl different use fctors, such s verge dily use time nd purpose of use. Our study lso found n ssocition between smrtphone dependency nd bnorml nxiety. These findings dd to the current knowledge bse concerning dependency on smrtphone use nd bnorml nxiety tht might be relted to smrtphone use nd dependency. The verge mount of time spent using smrtphone is rising yerly in Kore (from 124 minutes per dy in 2011 to 134 minutes per dy in 2012), nd use is concentrted hevily mong young people. More thn 77.1% of ll smrtphone users re ged yers, with smrtphone distribution rte in this ge rnge of pproximtely 98%. 34 These young people re t time

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