Changes in electronic cigarette use from 2013 to 2015 and reasons for use among Finnish adolescents

In e na ional Jou nal o En i onmen al Resea ch and Public Heal h A icle Changes in Elec onic Ciga e e Use om 2013 o 2015 and Reasons o Use among Finnish Adolescen s Jaana M. Kinnunen 1,*, Hanna Ollila 2, Pi jo L. Lind o s 1,3 and A ja H. Rimpelä 1,3,4 1School o Heal h Sciences, Uni e si y o Tampe e, 33014 Tampe e, Finland; [email p o ec ed] (P.L.L.); [email p o ec ed] (A.H.R.) 2 Depa men o Heal h, Na ional Ins i u e o Heal h and Wel a e, 00271 Helsinki, Finland; [email p o ec ed] 3PERLA—Tampe e Cen e o Childhood, You h and Family Resea ch, Uni e si y o Tampe e, 33014 Tampe e, Finland 4Depa men o Adolescen Psychia y, Pi käniemi Hospi al, Tampe e Uni e si y Hospi al, 33380 Nokia, Finland *Co espondence: [email p o ec ed]; Tel.: +358-40-190-1667 Academic Edi o : Paul B. Tchounwou Recei ed: 2 Sep embe 2016; Accep ed: 4 No embe 2016; Published: 9 No embe 2016 Abs ac : Elec onic ciga e es a e qui e a new po en ial sou ce o nico ine addic ion among you h. Mo e esea ch is needed, pa icula ly on e-liquid use and socioeconomic ac o s as po en ial de e minan s. We s udied changes om 2013 o 2015 in adolescen e-ciga e e awa eness and e e -use, ypes o e-liquids, and de e minan s in Finland. In 2015, we s udied weekly use and easons o e e -use. Da a we e om wo na ional su eys o 12–18-yea -old Finns (2013, n= 3535, esponse a e 38%; 2015, n= 6698, 41%). Desc ip i e s a is ics and logis ic eg ession analysis we e used. Awa eness and e e -use o e-ciga e es inc eased signi ican ly om 2013 o 2015 in all age and gende g oups. E e -use inc eased om 17.4% o 25%, wi h hal ha ing ied nico ine e-liquids. In 2015, weekly use was a e (1.5%). Daily ciga e e smoking was he s onges de e minan (OR 51.75; 95% CI 38.18–70.14) o e-ciga e e e e -use, as o e-ciga e e weekly use, bu smoking expe imen a ion and e e -use o snus (Swedish ype mois snu ) and wa e pipes alongside pa en al smoking and poo academic achie emen also inc eased he odds o e e -use. The mos common eason behind e-ciga e e e e -use was he desi e o y some hing new. To conclude, adolescen e-ciga e e e e -use is inc easing, and also among ne e -smoke s. Tobacco- ela ed ac o s a e s onge de e minan s o e-ciga e e use han socioeconomic ac o s. Keywo ds: elec onic ciga e e; elec onic nico ine deli e y sys em; adolescen s; obacco use; Finland 1. In oduc ion Awa eness and use o elec onic ciga e es (e-ciga e es) o elec onic nico ine deli e y sys ems (ENDS) has been inc easing bo h among adul s and adolescen s [ 1 – 4 ]. E-ciga e e expe imen a ion ( ied a leas once) and mo e egula use seem o cen e on younge smoke s, bu a e no limi ed o hem—g owing p opo ions o e-ciga e e use among ne e -smoking adolescen s and young adul s a e being epo ed [5,6]. Only a hand ul o s udies ha e speci ically inqui ed abou he easons o mo i es behind adolescen e-ciga e e expe imen a ion o use. Kong e al. [ 7 ] ound ha he op easons o expe imen a ion among U.S. you h we e cu iosi y, appealing la o s and pee in luences. Cu iosi y has been ci ed by eenage s as he op eason also in Swi ze land [ 8 ] and in New Zealand [ 4 ]. Top easons o discon inua ion in he U.S. s udy [ 7 ] we e losing in e es , pe cei ing e-ciga e es as “uncool” and exp essing heal h conce ns. Adolescen ciga e e smoke s pe cei ed ha e-ciga e es can also be used in places whe e smoking is p ohibi ed, which is wha led hem o y e-ciga e es. Ano he eason In . J. En i on. Res. Public Heal h 2016,13, 1114; doi:10.3390/ije ph13111114 www.mdpi.com/jou nal/ije ph In . J. En i on. Res. Public Heal h 2016,13, 1114 2 o 13 o adolescen ciga e e smoke s o y e-ciga e es was o qui smoking. They discon inued hei use mos ly because e-ciga e es we e no as sa is ying o hem as ciga e es [7]. E-ciga e e expe imen a ion and use ha e been associa ed among you h wi h suscep ibili y o con en ional ciga e e smoking ini ia ion [ 6 , 9 ], con en ional ciga e e smoking [ 4 , 5 , 8 , 10 – 17 ], male gende [ 4 , 8 , 12 , 13 , 15 ], e e -use o o he obacco (combus ible and non-combus ible) [ 10 , 11 , 13 ], alcohol use [ 4 , 8 , 13 , 17 ], pe cep ion o low ha m o e-ciga e es [ 18 – 21 ], pee smoking beha io [ 4 , 12 , 17 , 20 ], pa en s’ smoking [ 20 , 22 ], pee e-ciga e e use [ 23 ] and exposu e o e-ciga e e ad e ising [ 24 , 25 ]. Socioeconomic ac o s ha e been s udied less, and hei associa ion wi h e-ciga e e use is no so clea . Howe e , adolescen ’s oca ional educa ion [ 8 , 10 ], poo academic achie emen [ 10 ], a ending disad an aged school [ 15 ], and pa en s’ lowe educa ional le el [ 17 ] ha e been ound o be associa ed wi h e-ciga e e expe imen a ion and use. Al hough e-ciga e es a e ma ke ed as a smoking cessa ion ool [ 26 , 27 ], he a ailable c oss-sec ional s udies a ely show any associa ion be ween e-ciga e e use and smoking cessa ion o in en ion o qui smoking among you h [ 4 , 5 , 10 ]. The associa ed ac o s wi h egula use (daily o weekly use) o e-ciga e es, and, as such, ha e no been s udied be o e (see [8]). S udies on adolescen e-ciga e e use ha e paid li le a en ion o he ac ual con en s o e-liquids, besides la o s, in s udies o adolescen e-ciga e e use. Adolescen s’ use o e-liquids con aining nico ine aises conce n, as i may cons i u e a isk o nico ine dependence, and nico ine may ha e a las ing e ec on adolescen s’ de eloping b ains [ 28 , 29 ]. Kinnunen e al. [ 10 ] we e he i s o epo ha he majo i y o Finnish adolescen e-ciga e e e e -use s had indeed used nico ine-con aining e-liquids. The e-liquid con en s a e an impo an esea ch ques ion no only in e ms o p e en ing nico ine addic ion, bu also om he pe spec i e o p oduc egula ion and you h access laws. A he ime o ou su eys in 2013 and 2015, he Finnish obacco legisla ion p ohibi ed selling obacco p oduc s o you h unde 18 yea s old, bu his did no conce n e-ciga e es, as hey we e classi ied as obacco imi a ions and e-liquids as subs i u e obacco. Thus, mino s could pu chase hem eely when hey we e a ailable in he shops. By con as , nico ine-con aining e-ciga e es and e-liquids we e ea ed as medicinal p oduc s, meaning ha s ic sa e y and e icacy e idence mus ha e been demons a ed be o e a selling pe mi was g an ed. A he momen o he su eys, no e-ciga e e company had a selling pe mi o nico ine-con aining e-liquids in Finland. Howe e , hey could be acqui ed om isi s ab oad o online by consume s, including adolescen s. Mos mino s indeed epo ed ge ing hei e-ciga e es mainly om iends o online [10]. In his s udy, we epo changes om 2013 o 2015 in he awa eness and use o e-ciga e es and in he use o nico ine and non-nico ine e-liquids using na ionally ep esen a i e da a o 12–18-yea -old Finns. Fu he mo e, we in es iga e whe he he de e minan s o e-ciga e e e e -use ha e changed du ing he wo-yea pe iod. We also s udy egula use o e-ciga e es, de e minan s o weekly e-ciga e e use, and easons o e-ciga e e use in 2015. 2. Ma e ials and Me hods 2.1. Sampling and Pa icipan s This s udy was based on he na ionally ep esen a i e da a collec ed as pa o he 2013 and 2015 Adolescen Heal h and Li es yle Su ey, which is a c oss-sec ional pos al su ey o in es iga e adolescen heal h and heal h beha io s. I has been conduc ed biennially in Finland since 1977, wi h an op ion o answe also ia a p o ec ed online o m since 2009. Na ionally ep esen a i e samples o 12-, 14-, 16- and 18-yea -olds we e ob ained om The Popula ion Regis e Cen e (Helsinki, Finland) [ 30 ]. All adolescen s bo n on ce ain days in June, July o Augus we e selec ed. The s udy p ocedu e has been kep simila o enable compa isons be ween su ey yea s. The E hics Commi ee o he Tampe e Region, Finland app o ed he s udy p o ocol in 2013 and 2015 (Code: 4/2013 and 31/2014). Sel -adminis e ed ques ionnai es we e sen by mail o 9398 adolescen s in 2013 and o 16,473 adolescen s in Feb ua y 2015, ollowed by wo eminde s o non- esponden s. The numbe o esponden s in 2013 was 3535 ( esponse a e 38%), and, in 2015, 6698 ( esponse a e 41%). In . J. En i on. Res. Public Heal h 2016,13, 1114 3 o 13 Gi ls esponded mo e ac i ely han boys: in 2013, he esponse a e o gi ls was 46% and o boys 30%, and, in 2015, 47% and 34%, espec i ely. 2.2. The Measu es The awa eness and use o e-ciga e es was assessed in bo h yea s by posing he ques ions: “Ha e you e e ied elec onic ciga e es? How many imes al oge he ?” The op ions we e: “I do no know wha hey a e”, “No”, “I ha e ied once o wice”, “I ha e ied 20 imes o less” and “I ha e ied mo e han 20 imes”. Fo he analysis o de e minan s o e-ciga e e e e -use, answe s o op ions “I do no know wha hey a e” and “No” we e classi ied as ne e -use o e-ciga e es, and he answe s o o he op ions as e e -use. To explo e he ypes o liquids used, he esponden s we e asked “I you ha e used elec onic ciga e es, wha subs ance did hey con ain?”, and hey could choose one o mo e o he ollowing op ions: “Liquid wi h nico ine”, “Liquid wi hou nico ine” and “I do no know”, and, in 2015, also “Some hing else, wha ?” (an open-ended op ion). Regula use was es ima ed only in 2015 wi h a ques ion: “Which one o he ollowing al e na i es bes desc ibes you cu en use o e-ciga e es?” wi h he op ions “I do no use e-ciga e es”, “I use e-ciga e es less han once a week”, “I use e-ciga e es once a week o mo e o en, bu no daily” and “I use e-ciga e es once a day o mo e o en”. Fo he analysis o de e minan s o e-ciga e e weekly use, answe s o op ions “I use e-ciga e es once a week o mo e o en, bu no daily” and “I use e-ciga e es once a day o mo e o en” we e classi ied as weekly use o e-ciga e es. The ques ion on he easons o e-ciga e e use was: “Wha we e he mos impo an easons why you ied an e-ciga e e o s a ed using hem?” The op ions we e “I wan ed o y some hing new”, “I wan ed o s op smoking”, “My iends s a ed o use hem” and an open-ended “Some hing else, wha ?” The esponden could epo mo e han one eason. In he analysis o de e minan s, he ollowing obacco ela ed ac o s we e used: smoking s a us, snus (Swedish ype mois snu ) use, wa e pipe use, pa en s’ smoking, and exposu e o e-ciga e e ad e ising, which we e all sel - epo ed by he adolescen s. The socioeconomic ac o s we e sel - epo ed academic achie emen in compa ison wi h class a e age, amily s uc u e, pa en s’ wo k si ua ion, and pa en s’ educa ion, which was ca ego ized acco ding o he highes educa ional le el o he pa en s. 2.3. Analysis o Non-Response Fo he analyses o non- esponse, a sho e ques ionnai e was sen o he non- esponden s. Those who answe ed he o iginal ques ionnai e we e compa ed wi h hose who answe ed he sho ques ionnai e, which was sen wi h he hi d eminde o non- esponden s. I included he main ques ions on obacco and e-ciga e e use. I was assumed ha he esponden s o he sho ques ionnai e ep esen closely all non- esponden s. The numbe o esponden s o he sho ques ionnai e was 623 in 2013 and 714 in 2015. The g oups did no di e by e-ciga e e e e -use (p= 0.502 in 2013 and p= 0.393 in 2015), weekly use (p= 0.679 in 2015) o by age (p= 0.216 in 2013 and p= 0.972 in 2015). Boys we e mo e likely o be non- esponden s in 2013 (p= 0.01), bu no in 2015 (p= 0.103). Adolescen s wi h low o a e age academic achie emen we e mo e likely o be non- esponden s (p= 0.024 in 2013 and p< 0.001 in 2015). 2.4. Da a Analysis Awa eness, use and egula use o e-ciga e es we e c oss- abula ed wi h age, gende , obacco use and socioeconomic ac o s. Di ec adjus men , gi ing equal weigh s o each g oup, was used o calcula e age- and gende -adjus ed p e alence. E-liquids and easons o e-ciga e e use a e p esen ed o hose who had used e-ciga e es. Bina y and s epwise logis ic eg ession analyses we e used o analyze he ac o s associa ed wi h e e -use o e-ciga e es om he pooled da a o bo h yea s. Fi s , he analysis was conduc ed sepa a ely o all independen a iables, including su ey yea , adjus ing o age and gende . Then, all independen a iables we e included in a mul i a ia e model. The ac o s associa ed wi h In . J. En i on. Res. Public Heal h 2016,13, 1114 4 o 13 weekly use o e-ciga e es we e analyzed om 2015 da a he same way as o e e -use, bu wi hou su ey yea . The Pea son χ2 es was used o es s a is ical di e ences. SPSS S a is ics V.23 (IBM, A monk, NY, USA) was used o all da a analyses. 3. Resul s 3.1. Awa eness and Use o E-Ciga e es Awa eness o e-ciga e es inc eased om 2013 o 2015 in Finland (Table 1). In 2013, 85.3% o he 12–18-yea -olds epo ed knowing wha e-ciga e es a e, while he p opo ion was 94.0% in 2015. O e all, 17.4% o he esponden s had ied e-ciga e es in 2013, and 25.0% in 2015 (p< 0.001). Mos adolescen s had ied e-ciga e es only once o wice (12.6% in 2013 and 16.4% in 2015). The p opo ion o hose who had ied e-ciga e es mo e han 20 imes had isen om 2.0% o 4.7%. The e-ciga e e expe imen a ion and use inc eased om 2013 o 2015 among bo h gende s. Boys had expe imen ed mo e o en han gi ls, p< 0.001 (Table 1). Table 1. Dis ibu ion o e-ciga e e expe imen a ion among adolescen s in Finland in 2013 and 2015 and p- alue o di e ences be ween yea s, and egula use in 2015, by gende and age, %. The o al columns a e adjus ed o age. Boys|Age 12 14 16 18 To al, % Yea 2013 2015 2013 2015 2013 2015 2013 2015 2013 2015 E e -use o e-ciga e es Do no know wha hey a e 29.3 13.9 9.9 3.7 4.9 1.6 5.8 1.3 12.5 5.1 Ne e ied 68.4 81.8 70.6 74.1 66.6 57.8 62.8 53.3 67.1 66.8 Ha e ied once o wice 1.6 3.7 15.3 15.9 19.5 24.6 20.6 24.3 14.3 17.1 Ha e ied 20 imes o less 0.8 0.3 3.2 3.4 3.7 7.0 5.1 7.3 3.2 4.5 Ha e ied mo e han 20 imes - 0.3 1.0 2.9 5.3 9.1 5.8 13.8 3.0 6.5 To al, % 100 100 100 100 100 100 100 100 - - n256 649 405 893 431 703 277 593 1369 2838 p- alue <0.001 <0.001 <0.001 <0.001 <0.001 Regula use o e-ciga e es * I do no use e-ciga e es egula ly 99.5 96.3 89.6 89.8 93.8 Less han once a week 0.5 2.6 7.1 5.4 3.9 Once a week o mo e o en bu no daily - 0.6 1.9 0.9 0.9 Once a day o mo e o en - 0.6 1.3 3.9 1.5 To al, % 100 100 100 100 - n612 854 673 571 2710 Gi ls|Age 12 14 16 18 To al, % Yea 2013 2015 2013 2015 2013 2015 2013 2015 2013 2015 E e -use o e-ciga e es Do no know wha 43.8 20.6 13.3 3.8 7.2 2.0 3.2 0.7 16.9 6.8 hey a e Ne e ied 55.9 77.9 74.5 82.6 72.7 66.6 73.2 59.0 69.1 71.5 Ha e ied once o wice 0.3 1.5 9.1 9.0 15.3 21.4 18.4 30.3 10.8 15.6 Ha e ied 20 imes o less - - 2.5 2.3 3.2 5.4 3.7 5.4 2.4 3.3 Ha e ied mo e han 20 imes - - 0.7 2.4 1.7 4.7 1.6 4.6 1.0 2.9 To al, % 100 100 100 100 100 100 100 100 - - n288 678 596 1090 596 1075 626 952 2106 3795 p- alue <0.001 <0.001 <0.001 <0.001 <0.001 Regula use o e-ciga e es * I do no use e-ciga e es egula ly 99.7 96.8 94.0 94.4 96.2 Less han once a week 0.3 2.4 4.9 4.0 2.9 Once a week o mo e o en bu no daily - 0.8 1.0 1.1 0.7 Once a day o mo e o en - 0.1 0.1 0.5 0.2 To al, % 100 100 100 100 - n649 1053 1052 929 3683 * No asked in 2013. In . J. En i on. Res. Public Heal h 2016,13, 1114 5 o 13 Mos o hose who had ied e-ciga e es had also ied con en ional ciga e es (91.5% in 2013 and 83.3% in 2015) (no shown in a able). In 2013, 42.3% o hose who had ied con en ional ciga e es had also ied e-ciga e es, while he p opo ion was 64.1% in 2015. O hose who had ne e ied con en ional ciga e es, 2.6% had ied e-ciga e es a leas once in 2013 and 6.3% in 2015. Among 12-yea -old ne e -smoke s, expe imen ing was less equen (0.4% in 2013 and 1.5% in 2015) han among olde age g oups. In 2015, 0.7% o ne e -smoke s had ied e-ciga e es mo e han wice, while he p opo ion was 0% in 2013. In 2015, 1.5% o all esponden s epo ed e-ciga e e use a leas weekly, and 3.4% less han once a week. Regula use o e-ciga e es was e y a e among 12-yea -olds, bu i became mo e common wi h age (Table 1). Daily use o e-ciga e es was mos common among 18-yea -old boys (3.9%). The di e ence in egula use o e-ciga e es be ween boys and gi ls was s a is ically signi ican (p< 0.001). 3.2. Nico ine and Non-Nico ine Con aining E-Liquids Among he e-ciga e e use s, e-liquid con aining nico ine was used mo e o en han liquid wi hou nico ine, bu i s p opo ion dec eased om 2013 o 2015 (Table 2). The p opo ion o hose who did no know he con en o he liquid almos doubled om 2013 o 2015. Among hose e-ciga e e expe imen e s who had ne e ied con en ional ciga e es, liquids wi hou nico ine we e used mos o en, bu one i h o hem had used liquids wi h nico ine in 2015 (Table 2). Table 2. Dis ibu ion o e-ciga e e liquids among all e-ciga e e use s and among hose e-ciga e e use s who had ied and hose who had ne e ied con en ional ciga e es in 2013 and 2015, %. T ied Con en ional Ciga e es, % Ne e T ied Con en ional Ciga e es, % All E-Ciga e e Use s, % Type o Liquid|Yea 2013 2015 2013 2015 2013 2015 Liquids wi h nico ine 69.3 55.9 22.2 21.1 65.3 50.2 Only liquids wi hou nico ine 20.4 25.2 59.3 52.4 23.5 29.7 Do no know 10.4 18.8 18.5 26.5 11.1 20.0 To al, % 100 100 100 100 100 100 n579 1375 54 275 637 1661 p- alue <0.001 0.454 <0.001 Among all esponden s who had ne e ied con en ional ciga e es, 1.3% had used nico ine-con aining e-ciga e e in 2015, and 0.6% in 2013 (no shown in a able). Among he esponden s who we e e e -smoke s, he co esponding p opo ions we e 35.7% in 2015 and 29.0% in 2013. In 2015, o hose who had ied e-ciga e es once o wice, 38.2% had used liquids wi h nico ine and 34.2% had used only liquids wi hou nico ine, while, in 2013, he p opo ions we e 59.0% and 26.5%, espec i ely (no shown in a able). Mos o hose who had used e-ciga e es mo e han 20 imes had used liquids wi h nico ine (mo e han 80% in bo h yea s). The highes p opo ion (27.6% in 2015 and 14.5% in 2013) o hose who did no know wha e-liquid hey had used was among hose who had ied e-ciga e es only once o wice. 3.3. Reasons o E-Ciga e e Expe imen a ion and Use Reasons o e-ciga e e expe imen a ion and use we e asked in 2015. Adolescen s’ mos epo ed eason was “I wan ed o y some hing new”; his was epo ed by 61.4% o hose who had ied e-ciga e es (Figu e 1). “My iends s a ed o use hem” was epo ed by 23.4% o e-ciga e e expe imen e s and use s, and “I wan ed o qui smoking” by 12.9%. Some o he eason was gi en by 15.7%, and i included easons like “ he la o possibili ies”, “an oppo uni y o y came my way” and “ he icks wi h smoke/s eam”. I was possible o epo mo e han one eason. In . J. En i on. Res. Public Heal h 2016,13, 1114 6 o 13 Figu e 1shows also he p opo ions o easons o e-ciga e e expe imen a ion and use among hose who had ied e-ciga e es only once o wice and among hose who had used hem mo e han ha . Those adolescen s who had used e-ciga e es mo e han jus a couple o imes epo ed mo e o en ha “I wan ed o qui smoking” and “My iends s a ed o use hem” han hose who had expe imen ed only once o wice. In . J. En i on. Res. Public Heal h 2016, 13, 1114 6 o 13 15.7%, and i included easons like “ he la o possibili ies”, “an oppo uni y o y came my way” and “ he icks wi h smoke/s eam”. I was possible o epo mo e han one eason. Figu e 1 shows also he p opo ions o easons o e-ciga e e expe imen a ion and use among hose who had ied e-ciga e es only once o wice and among hose who had used hem mo e han ha . Those adolescen s who had used e-ciga e es mo e han jus a couple o imes epo ed mo e o en ha “I wan ed o qui smoking” and “My iends s a ed o use hem” han hose who had expe imen ed only once o wice. Figu e 1. Reasons o e-ciga e e expe imen a ion and use among all e-ciga e e e e -use s and by he equency o e-ciga e e use in 2015, %. 3.4. De e minan s o E-Ciga e e Use Table 3 p esen s he de e minan s o e-ciga e e e e -use. In Model 1 (adjus ed o age, gende and su ey yea ), along wi h male gende , all obacco- ela ed and socioeconomic backg ound a iables, excluding a he ’s wo k si ua ion, had a signi ican associa ion wi h e-ciga e e expe imen a ion in pooled da a o bo h su ey yea s (Table 3). The s onges associa ions we e obse ed o daily smoking and smoking expe imen a ion, ollowed by snus and wa e pipe use. Exposu e o e-ciga e e ad e isemen s and pa en s’ smoking we e also posi i ely associa ed wi h e-ciga e e expe imen a ion. Among socioeconomic cha ac e is ics, adolescen s’ academic achie emen was mo e s ongly ela ed o e-ciga e e use han amily s uc u e, pa en s’ educa ion o pa en s’ wo king si ua ions. In he inal model (Model 2, Table 3) adjus ing o all a iables, e-ciga e e use showed he s onges associa ion wi h con en ional ciga e e smoking, ollowed by snus and wa e pipe use, and male gende . Among socioeconomic cha ac e is ics, only ha ing poo e academic achie emen e ained a posi i e signi ican associa ion wi h e-ciga e e use. The in e ac ions be ween each a iable in Model 2 and he su ey yea we e also es ed. The only in e ac ion ha emained s a is ically signi ican in he inal Model 2 was he in e ac ion be ween wa e pipe use and he su ey yea . The odds a ios o e-ciga e e use among hose who had ied wa e pipe we e 6.54 (95% CI 5.27–8.12) in 2013, and 9.66 (8.15–11.45) in 2015. Figu e 1. Reasons o e-ciga e e expe imen a ion and use among all e-ciga e e e e -use s and by he equency o e-ciga e e use in 2015, %. 3.4. De e minan s o E-Ciga e e Use Table 3p esen s he de e minan s o e-ciga e e e e -use. In Model 1 (adjus ed o age, gende and su ey yea ), along wi h male gende , all obacco- ela ed and socioeconomic backg ound a iables, excluding a he ’s wo k si ua ion, had a signi ican associa ion wi h e-ciga e e expe imen a ion in pooled da a o bo h su ey yea s (Table 3). The s onges associa ions we e obse ed o daily smoking and smoking expe imen a ion, ollowed by snus and wa e pipe use. Exposu e o e-ciga e e ad e isemen s and pa en s’ smoking we e also posi i ely associa ed wi h e-ciga e e expe imen a ion. Among socioeconomic cha ac e is ics, adolescen s’ academic achie emen was mo e s ongly ela ed o e-ciga e e use han amily s uc u e, pa en s’ educa ion o pa en s’ wo king si ua ions. In he inal model (Model 2, Table 3) adjus ing o all a iables, e-ciga e e use showed he s onges associa ion wi h con en ional ciga e e smoking, ollowed by snus and wa e pipe use, and male gende . Among socioeconomic cha ac e is ics, only ha ing poo e academic achie emen e ained a posi i e signi ican associa ion wi h e-ciga e e use. The in e ac ions be ween each a iable in Model 2 and he su ey yea we e also es ed. The only in e ac ion ha emained s a is ically signi ican in he inal Model 2 was he in e ac ion be ween wa e pipe use and he su ey yea . The odds a ios o e-ciga e e use among hose who had ied wa e pipe we e 6.54 (95% CI 5.27–8.12) in 2013, and 9.66 (8.15–11.45) in 2015. Table 4p esen s he de e minan s o weekly use o e-ciga e es in 2015. In Model 1 in Table 4(adjus ed o age and gende ), daily smoking, smoking expe imen a ion, snus and wa e pipe use, pa en s’ smoking, academic achie emen , amily s uc u e and male gende had a signi ican associa ion wi h e-ciga e e weekly use (Table 4). In Model 2, daily smoking, smoking expe imen a ion, snus use, male gende and a he ’s smoking only e ained signi ican posi i e associa ions wi h e-ciga e e weekly use. In . J. En i on. Res. Public Heal h 2016,13, 1114 7 o 13 Table 3. Age and gende adjus ed p e alence (%) o e-ciga e e e e -use and odds a ios (OR) and he 95% con idence in e al o e-ciga e e use by gende , and obacco ela ed and socioeconomic ac o s, among 14–18-yea -olds in he pooled da a o 2013 and 2015. Cha ac e is ics nE e -Use o E-Ciga e es, % Model 1 * Model 2 † OR (95% CI) OR (95% CI) Su ey yea 2013 2931 22.6 1.00 1.00 2015 5306 32.3 1.67 (1.50–1.86) 2.42 (2.00–2.92) Age 14 2984 17.3 1.00 1.00 16 2805 31.8 2.27 (2.00–2.58) 1.09 (0.91–1.31) 18 2448 37.3 2.95 (2.60–3.36) 0.74 (0.61–0.91) Gende Gi l 4935 24.8 1.00 1.00 Boy 3302 32.8 1.52 (1.38–1.68) 1.48 (1.27–1.72) Tobacco ela ed ac o s Smoking s a us Ne e 4719 7.2 1.00 1.00 Expe imen e 2578 48.2 14.93 (12.85–17.34) 8.39 (7.03–10.00) Daily smoke 848 87.5 126.15 (98.58–161.43) 51.75 (38.18–70.14) Snus use Ne e 6547 16.2 1.00 1.00 E e 1676 72.5 13.14 (11.50–15.01) 3.14 (2.64–3.75) Wa e pipe use Ne e 6701 19.9 1.00 1.00 E e 1489 67.9 8.28 (7.25–9.45) 2.10 (1.57–2.80) Pa en s’ smoking Nei he o hem smokes 5703 24.8 1.00 1.00 Only mo he smokes 552 38.8 2.07 (1.72–2.50) 1.00 (0.75–1.32) Only a he smokes 1070 35.4 1.80 (1.56–2.09) 1.28 (1.04–1.57) Bo h o hem smoke 564 43.5 2.67 (2.22–3.21) 1.40 (1.06–1.85) Has seen e-ciga e e ad e isemen No 7368 28.2 1.00 n. s. Yes 729 38.2 1.72 (1.46–2.03) Socioeconomic backg ound Academic achie emen Much o sligh ly be e 4050 22.6 1.00 1.00 Abou class a e age 3178 31.9 1.68 (1.51–1.88) 1.24 (1.06–1.45) Sligh ly o much poo e 876 46.2 3.30 (2.82–3.87) 1.60 (1.26–2.03) Family s uc u e In ac amily 6430 26.9 1.00 n. s. O he amily ype 1752 35.4 1.56 (1.38–1.75) Pa en s’ educa ional le el High 2956 25.4 1.00 n. s. Middle 4649 30.6 1.32 (1.18–1.47) Low 136 31.4 1.50 (1.02–2.20) Fa he ’s wo k si ua ion Wo king 6856 28.7 1.00 n. s. No wo king 1007 29.0 1.02 (0.87–1.18) Mo he ’s wo k si ua ion Wo king 7161 28.4 1.00 n. s. No wo king 873 32.6 1.30 (1.12–1.52) * Model 1: Logis ic eg ession, adjus ed o age, gende and su ey yea ; † Model 2: S epwise o wa d logis ic eg ession; includes all a iables in Model 1. No e. Odds a io (OR) is gi en in bold ace when i indica es a s a is ically signi ican (p< 0.05) di e ence om he odds o he e e ence ca ego y. n. s. = no signi ican . In . J. En i on. Res. Public Heal h 2016,13, 1114 8 o 13 Table 4. Age and gende adjus ed p e alence (%) o e-ciga e e weekly use and odds a ios (OR) and he 95% con idence in e al o e-ciga e e use by gende and obacco ela ed and socioeconomic ac o s, among 14–18-yea -olds in 2015. Cha ac e is ics nWeekly Use o E-Ciga e es, % Model 1 * Model 2 † OR (95% CI) OR (95% CI) Su ey yea 2015 5132 2.1 Age 14 1907 1.1 1.00 n. s. 16 1725 2.2 2.05 (1.16–3.63) 18 1500 3.2 3.07 (1.77–5.31) Gende Gi l 3034 1.2 1.00 1.00 Boy 2098 3.1 2.62 (1.71–4.00) 2.58 (1.54–4.31) Tobacco ela ed ac o s Smoking s a us Ne e 3018 0.4 1.00 1.00 Expe imen e 1553 2.7 9.87 (4.52–21.52) 5.38 (2.07–13.98) Daily smoke 495 13.8 43.36 (19.65–95.71) 17.81 (6.48–48.97) Snus use Ne e 4053 0.8 1.00 1.00 E e 1075 6.0 7.25 (4.52–11.64) 2.98 (1.58–5.64) Wa e pipe use Ne e 4153 1.2 1.00 n. s. E e 955 5.7 5.00 (3.20–7.82) Pa en s’ smoking Nei he o hem smokes 3564 1.4 1.00 1.00 Only mo he smokes 348 3.1 2.28 (1.13–4.60) 1.27 (0.56–2.86) Only a he smokes 656 4.4 2.94 (1.74–4.96) 2.14 (1.18–3.87) Bo h o hem smoke 319 6.1 4.38 (2.43–7.90) 2.02 (1.00–4.09) Has seen e-ciga e e ad e isemen No 4697 2.1 1.00 n. s. Yes 385 2.7 1.49 (0.77–2.91) Socioeconomic backg ound Academic achie emen Much o sligh ly be e 2546 1.2 1.00 n. s. Abou class a e age 1994 2.6 2.21 (1.35–3.62) Sligh ly o much poo e 550 4.4 3.84 (2.14–6.91) Family s uc u e In ac amily 4017 1.7 1.00 n. s. O he amily ype 1080 3.5 2.14 (1.39–3.30) Pa en s’ educa ional le el High 1887 1.5 1.00 n. s. Middle 2885 2.3 1.51 (0.94–2.44) Low 70 1.7 1.08 (0.14–8.15) Fa he ’s wo k si ua ion Wo king 4311 2.1 1.00 n. s. No wo king 626 1.9 0.95 (0.50–1.80) Mo he ’s wo k si ua ion Wo king 4478 2.1 1.00 n. s. No wo king 550 2.8 1.34 (0.74–2.43) * Model 1: Logis ic eg ession, adjus ed o age and gende ; † Model 2: S epwise o wa d logis ic eg ession; includes all a iables in Model 1. No e: Odds a io (OR) is gi en in bold ace when i indica es a s a is ically signi ican (p< 0.05) di e ence om he odds o he e e ence ca ego y. n. s. = no signi ican . In . J. En i on. Res. Public Heal h 2016,13, 1114 9 o 13 4. Discussion Awa eness and use o e-ciga e es inc eased om 2013 o 2015 among Finnish adolescen s. In 2015, only 6% did no know wha e-ciga e es we e. A qua e o adolescen s (25%) had ied e-ciga e es in 2015, compa ed o 17% in 2013, bu weekly use was s ill a e. Hal o e-ciga e e use s had used e-liquids wi h nico ine, bu one i h did no know wha e-liquid hey had used. In addi ion, some adolescen s who had ne e ied con en ional ciga e es had ied nico ine-con aining e-ciga e es (1.3% o all ne e -smoke s). The p opo ion among all e e -smoke s was 36.9%. The mos common eason o y e-ciga e es was he desi e o y some hing new; only one ou h o hose who had used e-ciga e es mo e han wice epo ed qui ing smoking as he eason o y e-ciga e es. Adolescen e-ciga e e e e -use was associa ed wi h con en ional ciga e e smoking, and snus and wa e pipe use, bu also wi h lowe socioeconomic backg ound, mos o all wi h academic achie emen . Weekly use o e-ciga e es was associa ed signi ican ly only wi h obacco- ela ed ac o s. The esul s a e in line wi h o he s udies conce ning adolescen e-ciga e e use. The p opo ion o e-ciga e e expe imen e s in 2014 was also one ou h in Sweden, a neighbo ing coun y o Finland, and hal o he adolescen s had used liquids con aining nico ine [ 31 ]. A ecen s udy om U.S. [ 32 ] epo ed 20% o 12 h and 10 h g ade s, and 13% o 8 h g ade s using apo ize including nico ine a las use, which is less han in ou s udy. Inc ease in e-ciga e e use has been epo ed also om Poland [ 33 ], New Zealand [ 4 ] and he Uni ed S a es [ 34 ]. Regula use (a leas mon hly) o e-ciga e es among adolescen s was a e also in a s udy om he UK (2%) [ 35 ]. The de e minan s o e-ciga e e use in ou s udy a e in line wi h hose epo ed in o he s udies— o example con en ional ciga e e smoking [ 36 ] and o he obacco p oduc use [ 11 , 13 ]. In his s udy, socioeconomic ac o s we e associa ed wi h e-ciga e e expe imen a ion when s udied sepa a ely, bu when including hem in he same model wi h obacco- ela ed ac o s, only adolescen academic achie emen emained as a s a is ically signi ican de e minan . Ou s udy did no con i m pa en s’ lowe educa ional le el as a signi ican de e minan o e-ciga e e use ha was ound in Kale a e al. [ 17 ]. Cu iosi y has been de ec ed as an adolescen s’ mos common eason o e-ciga e e expe imen a ion in p e ious s udies [ 4 , 7 , 8 ], which has a simila meaning as a desi e o y some hing new. F iends’ in luences ha e also been epo ed p e iously [ 7 ]. Ou new esul s on de e minan s o weekly e-ciga e e use e ealed ha he de e minan s we e he same as o e-ciga e e e e -use, and ha only obacco- ela ed ac o s wi h male gende we e signi ican ly associa ed wi h i when included in he same model wi h socioeconomic backg ound ac o s. Howe e , weekly e-ciga e e use was a e (n= 94) leading o la ge con idence in e als, so hese esul s ha e o be in e p e ed wi h cau ion, and mo e esea ch is needed. Along wi h e-ciga e es, he e a e also o he new ENDS p oduc s, like e-hookahs o e-shishas and ape pens. The e is no clea classi ica ion sys em be ween hem, and you h seem o use p oduc cha ac e is ics like nico ine con en and cha geabili y when hey y o classi y hese di e en ENDS p oduc s [ 37 ]. The con en s and ypes o p oduc s also seem o ha e an impac on he pe cei ed appeal o he p oduc o he use p o o ype. Fo ins ance, e-hookah use s a e pe cei ed as young and endy bu e-ciga e e use s as old and addic ed o nico ine [37]. The new ENDS p oduc s may well be eplacing con en ional ciga e es in adolescen s’ smoking expe imen a ions. In he 2015 Adolescen Heal h and Li es yle Su ey [ 38 ], he age and gende adjus ed p e alence o ied con en ional ciga e e smoking among 12–18-yea -olds was 32%, only se en pe cen age uni s highe han he p e alence o ied e-ciga e es (25%). I emains o be seen whe he e-ciga e es a e he e o s ay, and adolescen s inc easingly expe imen wi h hem and dec easingly wi h con en ional ciga e es, o whe he e-ciga e es a e jus a passing ad o you h. In Finland, mino s ha e been able o buy non-nico ine e-ciga e es om shops wi hou any age limi s, and nico ine e-liquids om he in e ne . Usually, adolescen s ha e ob ained hese p oduc s om iends [ 10 ]. As he Finnish Tobacco Ac has been e ised in 2016 o comply wi h he new Eu opean Union Tobacco P oduc s Di ec i e (2014/40/EU) and also o in oduce new na ional egula ions [ 39 ], his si ua ion is now abou o change. Acco ding o he new legisla ion, e-ciga e es will be subjec o he same egula ions as obacco p oduc s, including sales p ohibi ion o mino s (18 yea s), poin -o