Pain from the masticatory structures, such as temporomandibular

Transcription

1 Comorbid Disorders ad Sociodemographic Variables i Temporomadibular Pai i the Geeral Dutch Populatio Corie M. Visscher, PhD Associate Professor Departmet of Oral Kiesiology MOVE Research Istitute Amsterdam Laie Ligthart, PhD Researcher Departmet of Biological Psychology Netherlads Twi Register VU Uiversity Amsterdam, ad EMGO+ Istitute for Health ad Care Research VU Uiversity Medical Cetre Aemarie A. Schuller, DDS, PhD Seior Scietist TNO Istitute for Applied Scietific Research Leide, ad Associate Professor Departmet of Detistry ad Oral Hygiee The Uiversity of Groige Groige, The Netherlads Frak Lobbezoo, DDS, PhD Professor Departmet of Oral Kiesiology MOVE Research Istitute Amsterdam Ad de Jogh, PhD Professor Departmet of Social Detistry ad Behavioural Scieces Hoorary Professor School of Health Scieces Salford Uiversity Machester, Uited Kigdom Carolie M.H.H. va Houtem, DDS PhD Studet Departmet of Social Detistry ad Behavioural Scieces Dorret I. Boomsma, PhD Professor Departmet of Biological Psychology Netherlads Twi Register VU Uiversity Amsterdam, ad EMGO+ Istitute for Health ad Care VU Uiversity Medical Cetre Correspodece to: Dr Corie M. Visscher Departmet of Oral Kiesiology (ACTA) MOVE Research Istitute Amsterdam Gustav Mahlerlaa LA Amsterdam The Netherlads c.visscher@acta.l 2015 by Quitessece Publishig Co Ic. Aims: (1) To determie the prevalece of temporomadibular disorder (TMD) pai complaits i the geeral Dutch populatio; (2) to ivestigate its relatioship with age, sex, educatioal attaimet, ad coutry of birth; (3) to determie its associatio with other pai complaits; ad (4) to determie whether there are TMD subgroups (ie, with regard to their sociodemographic variables) that are more vulerable for comorbid pai complaits. Methods: Data from two large-scale populatio studies were available: 975 radomly selected adults, who were iterviewed by a examier from the Istitute for Applied Scietific Research (TNO), ad 11,948 adults who were registered i the Netherlads Twi Register ad respoded to a survey questioaire. Chisquared tests ad regressio aalyses were used to determie whether there were ay associatios betwee the presece of TMD pai ad the various sociodemographic or comorbid variables. Results: The prevalece of TMDpai complaits was 7.2% to 8.0%, ad aroud twice as high i wome tha i me. The results were icoclusive for associatio with age, ad o evidece was foud for a associatio with coutry of birth or educatioal attaimet. TMD-pai complaits were strogly related to the presece of other pai complaits. Iterestigly, the umber of reported comorbid complaits was related to all of the studied sociodemographic variables. Coclusio: I the geeral Dutch populatio, wome more ofte report TMD-pai complaits tha me, ad patiets with TMD-pai complaits more ofte show other pai complaits tha persos without TMD pai. I cotrast to commo beliefs, o clear associatio with age was foud. Furthermore, widespread pai complaits were more commo i o-ative Dutch ad lower-educated females. J Oral Facial Pai Headache 2015;29: doi: /ofph.1324 Key words: pai comorbidity, prevalece, sociodemographic variables, temporomadibular-pai complaits Pai from the masticatory structures, such as temporomadibular disorder (TMD) pai, is the most commo source of chroic pai i the orofacial regio. 1 Similar to other chroic pai states, it is kow to impair physical fuctio 2 ad is associated with psychological problems, such as depressio ad axiety. 3 I additio, TMD pai may result i dimiished quality of life, 4,5 costly treatmets, ad reduced productivity. 6 For good health-care policies, epidemiologic data o the prevalece of specific pai disorders should be supplemeted with iformatio o the severity of the complaits (eg, i terms of its perseverace ad associatio with other disorders). TMD pai is ofte assumed to be most prevalet i wome i their early adulthood, 7 eve though empirical fidigs o age ad sex are icosistet. 8,9 For patiets with chroic TMD, associatios with other pai complaits, such as eck pai ad headaches, have frequetly bee reported However, these data are largely based o patiet samples from secodary care cliics with relatively severe pai complaits, ad they may ot be represetative of TMD pai patiets i the geeral populatio. Moreover, while there is evidece for social ad ethic disparities i pai experieces for may health coditios, 13 such differeces i TMD patiets have ot bee well documeted. 9 Joural of Oral & Facial Pai ad Headache 51

2 Therefore, the aims of this study were to (1) determie the prevalece of TMD-pai complaits i the geeral Dutch populatio; (2) ivestigate its relatioship with age, sex, educatioal attaimet, ad coutry of birth; (3) determie its associatio with other pai complaits; ad (4) determie whether there are TMD subgroups (ie, with regard to their sociodemographic variables) that are more vulerable for comorbid pai complaits. Materials ad Methods The data preseted i this article were derived from two idepedet large-scale study populatio-based cohorts. The first populatio sample cosisted of a radom selectio of persos from the geeral populatio, aged 25 to 74, as icluded i the databak available from the Istitute for Applied Scietific Research (TNO). The secod sample cosisted of adult participats registered with the Netherlads Twi Register (NTR: Sample 1 TNO As part of a cotiuig epidemiologic study of the geeral Dutch populatio, i 2007, a detal survey was performed amog the populatio of the city of s Hertogebosch, The Netherlads. This populatio is cosidered represetative of the geeral Dutch populatio i terms of age distributio, family compositio, percetage of o-dutch ihabitats, ad oral health. 14 The predomiat health isurace compay i s Hertogebosch (VGZ-IZA) provided cotact iformatio of a radom selectio of 6,750 persos from its database. From this group, a radom subgroup of 1,356 persos was selected ad iformed about the study by letter. I this letter, it was idicated that they could expect a home visit by a traied iterviewer of TNO withi the ext couple of weeks, ad that they were ivited for a subsequet cliical examiatio i a mobile oral health facility (detal va). I case the selected perso was ot at home at three differet home visits or did ot wish to participate, a substitute perso was selected (matched for age, geder, ad type of isurace as idicator for socioecoomic status). After 14 rouds of selectig substitute persos, recruitmet was stopped. At that time poit, 4,533 persos, aged 25 to 74 years, were selected for possible participatio i the study ad iformed by letter. The iterviewer was able to cotact 2,395 persos, ad 1,622 persos were willig to participate i the iterview (respose rate: 68%). Reasos for ot participatig were ot iterested (50%), o time (39%), or other reasos (31%) (multiple aswers possible). From the orespoders ( = 773), 32% ( = 246) were willig to aswer a short orespodet questioaire. A oparticipatio aalysis revealed that respoders were higher educated (highly educated respoders: 43%; highly educated orespoders: 31%; χ 2 =10.10; df = 1; P =.001). No differeces betwee respoders ad orespoders were foud regardig age, sex, ad ethicity. Measures i the TNO Sample Durig the home iterview, a wide rage of variables was collected, of which the followig were used i this study: Sociodemographic characteristics Age (stratified as 25 to 34 years, 35 to 44 years, 45 to 54 years, 55 to 64 years, ad 65 to 74 years). Sex (male/female). Coutry of birth (o-ative Dutch/ative Dutch) based o the participat s coutry of birth (The Netherlads versus ay other coutry). Educatioal attaimet (low/high); educatio was regarded high whe at least a higher-level geeral secodary educatio (HAVO) or tertiary school (ie, vocatioal college or uiversity) was completed. All other educatio was defied as low educatio. TMD-pai complaits After the iterview, persos with a atural detitio (ie, at least oe atural tooth, = 1,407) were ivited to participate i a subsequet cliical assessmet i the detal va, which was performed by a detal examier. From the detate respoders, 975 (69%) atteded the va. Their mea age was 47.5 years (SD = 12.5), ad 54% were female. Durig the cliical assessmet, the coditio of the atural teeth ad surroudig soft tissues was checked, ad the presece ad type of prosthodotic appliaces were oted (for more details, see 15 ). I additio, the followig questios about temporomadibular pai were asked: Have you experieced pai, at least ow ad the, i the regio of your temporomadibular joit or masticatory muscles whe you ope your mouth widely? (o/yes) Have you experieced pai, at least ow ad the, i the regio of your temporomadibular joit or masticatory muscles while chewig? (o/yes) Have you experieced, at least ow ad the, pai i the regio of your temporomadibular joit or masticatory muscles durig other madibular movemets? (o/yes) 52 Volume 29, Number 1, 2015

3 The detists performig the cliical assessmet poited toward the areas of iterest (beig the masticatory muscles ad the temporomadibular joits) ad explaied to the patiet that if they had oly experieced pai occasioally, it was ot cosidered relevat. No additioal TMD examiatios (such as palpatio tests) were performed. However, whe the pai complaits appeared to relate to a detal problem, the patiet was iformed that this pai was ot cosidered relevat for the TMD-pai questios. Patiets were classified as sufferig from a TMD-pai complait whe at least oe of the three questios was aswered positively. The ethics committee of the Leide Uiversity Medical Ceter cocluded that o formal applicatio was eeded for approval of the study because the procedures were harmless. The TNO study was performed i accordace with the ethical stadards laid dow i the 1964 Declaratio of Helsiki ad its later amedmets. All persos gave their iformed coset prior to their iclusio i the study, ad the study was registered at the Dutch Data Protectio Authority (o. m ). Sample 2 NTR The secod sample cosisted of adult twis ad their family members registered i the NTR. 16 Sice 1991, every 2 to 3 years the adult participats of the NTR are ivited to participate i a survey o physical ad metal health, lifestyle, ad persoality. As part of this cotiuig study, betwee Jauary 2011 ad February 2012 participats received a writte ivitatio to participate i a web-based survey that icluded questios regardig pai complaits (the ith wave of questioaire research, or Survey 9 ). A hard-copy versio of the questioaire was available o request. If subjects did ot complete the questioaire withi a few moths after the ivitatio was set, they received a writte remider. Whe ecessary, a secod remider was set. I July 2012, a geeral remider was set to selected groups of participats: a was set to those participats who had provided the NTR with their address, ad a remider was set to twis whose co-twi had already completed the questioaire. Fially, a selectio of participats who had ot completed the questioaire after the remiders were cotacted by telephoe, prioritizig participats who had previously supplied DNA samples to the NTR, or participats whose co-twi had completed the survey. From the total umber of 27,892 persos who were ivited to participate, 11,948 persos respoded (respose rate: 43%), comparable to previous studies i the adult NTR sample. 16 Of them, 6 persos were excluded because they were uder 18 years of age, ad aother 294 persos were excluded because they did ot fill i the TMD-pai questio. The remaiig subjects ( = 11,648, of 5,276 families) had a mea age (SD) of 44 (16) years (age rage 18 to 100 years), ad 62% were female. Measures i the NTR Sample The survey icluded questios about age ad sex. Iformatio regardig the participat s coutry of birth ad level of educatio was available from previous questioaire surveys that were set to the participats of the NTR. 16 Sociodemographic characteristics Age (stratified as 18 to 25 years, 25 to 34 years, 35 to 44 years, 45 to 54 years, 55 to 64 years, 65 to 74 years, > 74 years) Sex (male/female) Coutry of birth (o-ative Dutch/ative Dutch) Educatioal attaimet (low/high) TMD-pai ad other pai complaits The NTR survey also icluded questios about pai complaits. Participats were asked to report o a variety of pai complaits. The stem of the questio was: I the last year, did you experiece. The questios eded with: a) back ache b) eck ache c) headache or migraie d) pai i abdome or stomach e) pai i the joits (of arms, hads, legs or feet) f) pai o the chest g) toothache h) pai i the face (eg, cheeks, temples, or jaw joits) [from here o referred to as TMD-pai complaits] i) pai somewhere else:... [free text box] Respose optios were o ; yes, occasioally ; ad yes, a lot of the time. Whe a participat rated positive o a pai questio (ie, yes, occasioally or yes, a lot of the time ), a follow-up questio appeared to iquire about the cause of that pai (free text aswer). Afterwards, these free text aswers were screeed to exclude apparet false-positive aswers to the pai questios. For the TMD-pai questio (questio h), reasos to recode a positive aswer ito a egative aswer were: detal pai, eurologic pai, ad pai due to a cerebrovascular icidet or disease ( = 149, 1.4% of the total sample). If recodig led to Joural of Oral & Facial Pai ad Headache 53

4 loss of iformatio (ie, whe the recoded pai complait was ot already covered by oe of the other pai questios), questio i (pai somewhere else) was recoded ito yes, occasioally or yes, a lot of the time (accordig to the respose optio provided by the participat). The NTR survey was approved by the Medical Ethics Committee of the VU Uiversity Medical Ceter Amsterdam (r. 2010/130) ad followed the ethical stadards of the 1964 Declaratio of Helsiki ad its later amedmets. All participats gave their iformed coset prior to their iclusio i the study. Statistical Aalyses Descriptive statistics were produced usig SPSS 21.0 (IBM, 2012). First, for both populatio samples, the prevalece of TMD-pai complaits was determied for the total sample, ad for subsamples stratified by sex, age, ethicity, ad educatioal attaimet. For this aalysis, the NTR data o TMD pai complaits were dichotomized ito o-tmd pai ad TMD pai ( occasioally ad a lot of the time combied). For the TNO sample, chisquared tests were used to determie whether there were ay associatios betwee the prevalece of TMD pai ad the various sociodemographic variables (i SPSS 21.0). To correct for the o-idepedece of data derived from family members i the NTR sample, NTR-group differeces were tested with logistic regressio aalyses i STATA 12.1 (StataCorp), usig a robust variace estimator ad icludig family idetificatio (ID) as a cluster variable. Secod, ad oly for the NTR sample, prevalece data of the various other pai coditios i the patiets with TMD-pai complaits were preseted. Data o the presece of the various pai disorders were dichotomized ito o or yes ( occasioally ad a lot of the time combied). Additioally, a ew variable was calculated, called ay comorbid pai. This variable was scored as o whe o other pai complaits were reported, or as yes whe at least oe of the other pai questios (ie, excludig the TMD-pai questio) was rated as occasioally or a lot of the time. Logistic regressio aalyses, usig a robust variace estimator ad icludig family ID as a cluster variable, were used to test for a associatio betwee the various pai disorders ad the frequecy of TMD pai complaits (STATA 12.1). Third, a hierarchical liear regressio aalysis was performed with the total umber of comorbid pai complaits as the outcome measure, the frequecy of TMD pai complaits (o, occasioally, a lot of the time) as the mai predictor (etered i block 1), ad age, sex, ethicity, ad educatioal attaimet as potetial covariates (etered i block 2). The total comorbid pai variable represets the sum of the dichotomized pai variables, excludig TMD pai (rage: 0 to 8). Also for this aalysis, the robust variace estimator ad family ID as a cluster variable were used (STATA 12.1). The assumptios for liearity of the regressio aalysis (liear relatio of residuals, ormal distributio of the residuals, ad equal stadard deviatios of the residuals) were cofirmed by ispectio of the ormal P-P plot of regressio stadardized residual ad of the scatterplot of the stadardized residuals ad the stadardized predicted values. To correct for multiple testig, Holm s Boferroi procedure was used. 17 The Boferroi corrected P values are preseted, ad α =.05 was cosidered to reflect statistical sigificace. Results Associatio Betwee TMD-Pai Complaits ad Sociodemographic Variables Table 1 shows the prevalece of TMD-pai complaits i various subsamples from the two populatios. The overall prevalece of TMD-pai complaits i both study populatios was comparable: 7.2% ad 8.0%. I both samples, wome more frequetly reported complaits of TMD pai tha me, although the differece was oly sigificat i the NTR sample (OR = 2.2, P <.001). While i the TNO sample a associatio betwee age ad the prevalece of TMD-pai complaits was foud (it was highest i youg adults ad decreased with icreasig age; liear-by-liear associatio χ 2 = 7.75, df = 1, P =.020), this could ot be cofirmed i the NTR sample. No associatios were foud betwee TMD-pai complaits ad ethicity or educatioal attaimet (see Table 1). Associatio Betwee TMD-Pai Complaits ad Other Pai Complaits Table 2 presets the prevalece of the various pai complaits, other tha TMD pai, i the NTR sample. The most prevalet pai disorders were back pai, eck pai, joit pai, ad headache. For all pai complaits, the prevalece was higher i patiets with TMD-pai complaits as compared to those without TMD-pai complaits (OR = ; P <.001). Moreover, all of the participats with frequet TMDpai complaits ( a lot of the time ) had at least oe pai complait elsewhere ( ay comorbid pai, see Table 2). The total umber of comorbid pai complaits raged from 0 to 8. I Table 3, the mea umber of comorbid pai disorders is preseted, stratified by TMD-pai complaits, sex, age, educatioal attai- 54 Volume 29, Number 1, 2015

5 Table 1 Prevalece of TMD-Pai Complaits i the Two Study Samples, ad Stratified for the Various Sociodemographic Variables Sample 1 (TNO) Sample 2 (NTR) TMD pai TMD pai % (95% CI) Group diff a (P) % (95% CI) Group diff b (P) Total study populatio NA 11, NA 8.0% ( %) 7.2% ( %) Sex.168 <.001 Female % ( %) Male % ( %) 7, % ( %) 4, % ( %) Age (y) NA NA 2, % ( %) % ( %) % ( %) % ( %) % ( %) % ( %) 1, % ( %) 2, % ( %) 2, % ( %) 2, % ( %) % ( %) > 75 NA NA % ( %) Educatioal attaimet High % ( %) Low % ( %) 6, % ( %) 1, % ( %) Missig 21 NA 3,213 NA Coutry of birth Native Dutch % ( %) No-ative Dutch % ( %) 10, % ( %) % ( %) Missig 3 NA 968 NA a Differeces betwee groups i the TNO sample were aalyzed with χ 2 tests. b Differeces betwee groups i the NTR sample were aalyzed with logistic regressio aalyses. NA = ot applicable; 95% CI = 95% cofidece iterval; P = corrected P value (accordig to Holm s Boferroi correctio). Table 2 Prevalece of Comorbid Pai Complaits i Participats of the NTR Sample Pai complait No TMD pai Occasioal TMD pai TMD pai a lot of the time OR (95% CI) P Back pai 11, % 75.0% 86.2% 2.2 ( ) <.001 Neck pai 11, % 71.2% 85.1% 3.7 ( ) <.001 Headache 11, % 81.2% 75.5% 3.1 ( ) <.001 Pai i abdome or stomach 11, % 59.2% 57.1% 2.5 ( ) <.001 Joit pai 11, % 63.6% 73.7% 2.4 ( ) <.001 Chest pai 11, % 27.5% 31.6% 2.6 ( ) <.001 Toothache 11, % 24.7% 22.3% 2.0 ( ) <.001 Pai elsewhere 11, % 33.1% 29.2% 2.3 ( ) <.001 Ay comorbid pai 11, % 98.9% 100.0% 12.1 ( ) <.001 OR = odds ratio (from logistic regressio aalysis); 95% CI = 95% cofidece iterval; P = corrected P value (accordig to Holm s Boferroi correctio). Joural of Oral & Facial Pai ad Headache 55

6 Table 3 Hierarchical Liear Regressio Aalysis for the Other (Comorbid) Pai Disorders i Participats of the NTR Sample* Other pai disorders Model Mea (SD) b P R 2 P Block <.001 TMD pai 1.5 <.001 No pai 2.5 (1.7) Occasioally 4.3 (1.8) A lot of the time 4.6 (1.8) Block <.001 TMD pai 1.4 <.001 No pai 2.5 (1.7) Occasioally 4.3 (1.8) A lot of the time 4.6 (1.8) Sex 0.7 <.001 Male 2.2 (1.7) Female 3.0 (1.7) Age (1.8) (1.7) (1.7) (1.8) (1.7) (1.7) > (1.8) Educatioal attaimet <.001 Low 2.9 (1.8) High 2.6 (1.7) Coutry of birth Native Dutch 2.7 (1.7) No-ative Dutch 3.0 (1.8) *Due to missig data o comorbid pai, educatioal attaimet, ad coutry of birth, the umber of subjects icluded i the aalysis is 7,454. b = regressio coefficiet; R 2 = explaied variace of the regressio model; P = corrected P value (accordig to Holm s Boferroi correctio). met, ad ethicity. The hierarchical regressio aalysis shows that the umber of comorbid disorders was ot oly associated with the frequecy of the TMD-pai complait, but also (ad idepedetly) with sex, educatioal attaimet, ad ethicity. For age, a borderlie sigificat associatio with the umber of comorbid disorders was foud. Discussio The data from this epidemiologic study were derived from two large ad idepedet study samples, with quite differet study desigs. Iformatio o TMD-pai complaits was gathered durig a iterview i the TNO sample, whereas questioaires were used i the NTR sample. Also, the precise formulatio of the TMD-pai questios ad respose optios was differet. I both approaches, however, a comparable descriptio of the pai locatio was used (temporomadibular joit ad masticatory muscles versus jaw joit, cheeks, ad temples). I additio, the three-value respose of the NTR sample was recoded ito a yes (ie, occasioally ad a lot of the time combied) or o outcome, which improves the comparability with the TNO sample (where yes stads for at least ow ad the ). Moreover, i both studies, special attetio was give to the exclusio of detal pai (as the most frequet cause of orofacial pai) from the TMD-pai classificatio. Sice TMD pai is the secod most frequet cause of orofacial pai, 7 ad other causes (such as europathic ijury or maligacies) preset quite differetly ad are quite rare, the authors are cofidet that most, if ot all, cases ideed suffered from a TMD complait. The overall prevalece of TMD-pai complaits i the two study populatios was almost equivalet (7.2% ad 8.0%) ad quite comparable to that reported i other samples from the geeral populatio. 8,18 Together with the above-described argumets for comparability, this supports the assumptio that the same costruct (ie, TMD pai) was measured with the two differet approaches. Sex Differece Up to 90% of patiets attedig TMD pai cliics are wome. 19 Iterestigly, TMD-pai prevalece studies i the geeral populatio usually report much smaller differeces betwee me ad wome compared to studies i cliical samples. Wome are usually foud to report TMD pai twice as ofte as me. 8,19,20 Also i the preset study, TMD-pai complaits were 1.5 to 2 times more commo i wome as i me. There are several possible reasos for the higher prevalece of TMD pai i wome, icludig sex-specific differeces i pai perceptio. For example, experimetal studies have show that wome report more proouced pai resposes to oxious stimuli tha me Experimetally evoked pai also persists loger 25 ad leads to more temporal summatio 26,27 i wome. Still, the large discrepacy i the reported sex differece betwee populatio studies ad studies from cliical samples suggests that 56 Volume 29, Number 1, 2015

7 it is ot oly the perceptio of pai that leads to the higher level of care-seekig i wome. This icreased care-seekig behavior i female TMD-pai patiets seems to be related i part to fear of movemet: A recet study foud that, idepedet of pai itesity, high levels of pai-related fear of movemet were a predictor for care-seekig i wome but ot i me. 28 Apparetly, wome ot oly experiece their pai differetly from me, but also appreciate their pai i a differet way, which leads to a higher use of the health care system. Age Distributio TMD pai is ofte assumed to be most prevalet i youg ad middle-aged adults. 7 However, the scietific evidece for this assumptio is icosistet. 29 A ofte-cited review states that TMD pai usually declies i frequecy after age 45 to However, the reported differeces i prevalece rates of various age groups, as reported i the papers icluded i that review, were usually quite small (for example, i oe of the icluded studies: 8.3% i people < 45 years versus 7.2% i people > 45 years) ad ot tested for statistical sigificace. 18 A more recet, large populatio study i the Uited States showed that the prevalece of self-reported TMD pai i white wome icreased up to the age of 40 ad the decreased, while i Hispaic ad black wome, TMDpai prevalece icreased up to the age of 60. For me, smaller age differeces were foud. 30 I the preset study, the fidigs for the prevalece of TMD-pai complaits i differet age groups were icosistet. I the TNO sample, the yougest age group (25 to 34 years) had the highest report of TMD pai, ad a decrease i the prevalece of the pai complaits was foud with icreasig age. I the NTR sample, however, a quite stable patter of TMD-pai complaits was see over the various age groups. Also a multivariate aalysis with age, sex, ethicity, ad educatio did ot reveal ay relatioship betwee the various sociodemographic variables ad age, which could accout for the lack of associatio betwee age ad the prevalece of TMD pai (data ot preseted). Hece, there is isufficiet evidece for a associatio betwee age ad TMD pai. Coutry of Birth ad Educatioal Attaimet I geeral, the experiece of pai is ot uiformly distributed across ethic subgroups. 31 For example, results from a large populatio study idicated that Africa Americas ad Hispaic whites were more likely tha o-hispaic whites to report severe pai. 32 Comparable disparities i the prevalece of pai have bee described for subgroups with differet socioecoomic status. For istace, i headache patiets, lower socioecoomic status has bee associated with higher pai prevalece. 33 Eve though socioecoomic status ad ethic backgroud are itercorrelated, 34 i a aalysis of covariace cotrollig for pai duratio ad educatio, Africa America chroic-pai patiets reported higher levels of pai upleasatess ad emotioal resposes to pai ad pai behavior, but ot pai itesity, tha whites. 35 Cotrary to these fidigs, a review o eck pai i the geeral populatio foud o soud evidece for a associatio betwee musculoskeletal pai ad ethicity. 36 Much less has bee reported o the possible relatioship betwee ethicity, socioecoomic status, ad the presece of TMD-pai complaits. A epidemiologic survey i the geeral populatio foud o associatio betwee educatioal attaimet (college graduate) ad the prevalece of orofacial pai. 37 I a Dutch study of TMD patiets, o associatio was foud betwee ethic backgroud ad TMD pai, eve though o-wester TMD patiets had higher scores o psychologic factors, such as pairelated disability ad depressio. 38 Surprisigly, i a more recet populatio study i the Uited States, a higher prevalece of TMD complaits was reported by Caucasias as compared to ethic miorities (Hispaics ad Africa-Americas). 39 I the preset study, for both study samples, o associatio betwee the prevalece of TMD-pai complaits ad coutry of birth was foud, or was there ay associatio with educatioal attaimet. Perhaps differeces i the defiitios of ethicity applied may accout for the various study outcomes. I the preset study, the coutry of birth of the participat was used, ad thereby represeted whether the participat had moved to a ew coutry. I the previous Dutch study, a slightly differet approach was used: ethic backgroud was ot oly rated based o the coutry of birth of the TMD patiets, but also o that of their parets. 38 I both studies, however, o associatio with the presece of TMD pai was foud. I the US sample (where they did fid a associatio with the prevalece of TMD complaits), the racial backgroud of the participats, ot the coutry of birth, was used. 39 Dutch ihabitats are a very heterogeeous group with respect to their racial backgroud. So, take together, these fidigs might idicate that psychosocial or evirometal factors that are associated with movig to aother coutry (o-atives) are less importat predictors of TMD pai tha racial factors. At the same time, it is importat to ote that the ethic disparities reported for the US sample were foud oly for TMD-pai complaits, ot for other pai complaits such as back pai or eck pai. 39 Other Pai Complaits (Comorbidity) A strog associatio betwee TMD pai ad all other paiful coditios was foud. Persos with mild TMD Joural of Oral & Facial Pai ad Headache 57

8 pai showed approximately 1.5 times more comorbid pai complaits tha persos without TMD pai (Table 3), whereas persos with severe TMD-pai complaits showed approximately twice as may comorbid pai complaits. These results are i lie with earlier fidigs i samples of TMD patiets 40,41 ad populatio-based studies The hierarchical regressio aalysis showed that the associatio betwee TMD pai ad comorbidity was idepedet of the ifluece of sex, age, educatioal attaimet, ad ethicity. The aalysis also revealed that the umber of reported comorbid pai complaits was associated with each of the sociodemographic variables, eve though the associatio with age was weak. I other words, lower-educated females, ot bor i The Netherlads, ad with more frequet TMD-pai complaits, had the highest risk of sufferig from more widespread pai complaits. These results are i lie with ad expad upo earlier fidigs i a Dutch sample of TMD patiets, that o-ative o-wester patiets, idepedet of their socioecoomic backgroud, show more sigs of somatizatio. 38 The associatios betwee TMD-pai complaits ad the sociodemographic variables pose a iterestig questio: Is TMD pai a differet type of disorder as compared to the other pai complaits studied? Or is ot the locatio of pai, but merely the spreadig of pai related to the sociodemographic characteristics of the patiets? Further aalyses of the curret data are plaed to disetagle the associatio betwee specific pai complaits ad the sociodemographic variables. Coclusios The prevalece of TMD-pai complaits i the geeral Dutch populatio was 7.2% to 8.0%, ad approximately twice as high i wome as i me. I cotrast to commo beliefs, o clear associatio with age was foud. I additio, o evidece was foud for a associatio betwee TMD-pai complaits ad coutry of birth or educatioal attaimet. A strog associatio was foud betwee TMD-pai complaits ad the prevalece of other pai complaits. Furthermore, widespread pai complaits were more commo i o-ative Dutch ad lower-educated females. Ackowledgmets The Netherlads Twi Register ackowledges support from the Europea Research Coucil (ERC ), from the VU Uiversity Istitute for Health ad Care Research (EMGO+), ad the Neurosciece Campus Amsterdam (NCA). This project was additioally fuded by a grat of the Dutch Associatio for Orofacial Pai ad Prosthetic Detistry (NVGPT). The authors declare that they have o coflict of iterest. Refereces 1. Filligim RB, Wallace MR, Herbstma DM, Ribeiro-Dasilva M, Staud R. Geetic cotributios to pai: A review of fidigs i humas. Oral Dis 2008;14: Bush FM, Harkis SW. Pai-related limitatio i activities of daily livig i patiets with chroic orofacial pai: Psychometric properties of a disability idex. J Orofac Pai 1995;9: Vo Korff M, Simo G. The relatioship betwee pai ad depressio. Br J Psychiatry Suppl 1996;30: Campbell LC, Clauw DJ, Keefe FJ. Persistet pai ad depressio: A biopsychosocial perspective. Biol Psychiatry 2003; 54: Dahlstrom L, Carlsso GE. Temporomadibular disorders ad oral health-related quality of life. A case-cotrol study. J Orofac Pai 2001;15: Stowell AW, Gatchel RJ, Wildestei L. Cost-effectiveess of treatmets for temporomadibular disorders: Biopsychosocial itervetio versus treatmet as usual. J Am Det Assoc 2007; 138: De Leeuw R, Klasser GD (eds). Orofacial Pai: Guidelies for assessmet, diagosis, ad maagemet. Chicago: Quitessece, 2013: Carlsso GE. Epidemiology ad treatmet eed for temporomadibular disorders. J Orofac Pai 1999;13: Mafredii D, Guarda-Nardii L, Wiocur E, Piccotti F, Ahlberg J, Lobbezoo F. Research diagostic criteria for temporomadibular disorders: A systematic review of axis I epidemiologic fidigs. Oral Surg Oral Med Oral Pathol Oral Radiol Edod 2011;112: Visscher CM, Lobbezoo F, de Boer W, va der Zaag J, Naeije M. Prevalece of cervical spial pai i craiomadibular pai patiets. Eur J Oral Sci 2001;109: Bevilaqua Grossi D, Lipto RB, Bigal ME. Temporomadibular disorders ad migraie chroificatio. Curr Pai Headache Rep 2009;13: Browe PA, Clark GT, Kuboki T, Adachi NY. Cocurret cervical ad craiofacial pai. A review of empiric ad basic sciece evidece. Oral Surg Oral Med Oral Pathol Oral Radiol Edod 1998;86: Gree CR, Aderso KO, Baker TA, et al. The uequal burde of pai: Cofrotig racial ad ethic disparities i pai. Pai Med 2003;4: Schuller AA. Modgezodheid volwassee Leide: TNO Kwaliteit va Leve, Visscher CM, Lobbezoo F, Schuller AA. Detal status ad oral health-related quality of life. A populatio-based study. J Oral Rehabil 2014;41: Willemse G, Vik JM, Abdellaoui A, et al. The Adult Netherlads Twi Register: Twety-five years of survey ad biological data collectio. Twi Res Hum Geet 2013;16: Aicki M, Gesler H. Adjustig for multiple testig whe reportig research results: The Boferroi vs Holm methods. Am J Public Health 1996;86: Volume 29, Number 1, 2015

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