Vanessa Gisler, Renzo Bassetti, Regina Mericske-Stern, Stefan Bayer and Norbert Enkling

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1 Original article A cross-sectional analysis of the prevalence of dental anxiety and its relation to the oral health-related quality of life in patients with dental treatment needs at a university clinic in Switzerland Vanessa Gisler, Renzo Bassetti, Regina Mericske-Stern, Stefan Bayer and Norbert Enkling Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland doi: /j x A cross-sectional analysis of the prevalence of dental anxiety and its relation to the oral health-related quality of life in patients with dental treatment needs at a university clinic in Switzerland Objectives: The aim of this observational, cross-sectional study was to analyse the relationship between dental anxiety (DA) and health-related quality of life aspects associated with oral conditions of a population with dental treatment needs in Switzerland. Methods: The measurements of DA were collected by means of two questionnaires, the Dental Anxiety Scale (DAS) and a Visual Analogue Scale (VAS). Oral health-related quality of life (OHRQoL) was assessed with the Oral Health Impact Profile (OHIP). The sample included 223 patients enrolled at a university clinic which specialises in oral prosthetic rehabilitation and temporomandibular disorders. Of them, 78.9% were at or above the age of 50. Results: No gender or age dependencies were observed. A comparison of answers regarding OHRQoL and DA revealed a significant interdependence (p = ); highly anxious patients were 3.55 times more likely to suffer from poor quality of life compared with less anxious ones. Conclusion: This cross-sectional study of mostly elderly patients seeking dental treatment in Switzerland found that increased DA was associated with an impaired OHRQoL. The average DA was slightly higher than the results of other industrialised countries and the average OHRQoL was reduced. Keywords: dental anxiety, dental fear, oral health-related quality of life. Accepted 26 September 2010 Introduction In his daily practice, the dentist has to face the problem of dental anxiety (DA). Anxiety associated with dental treatment has been ranked fifth among common fears in a general population 1, and the prevalence of DA has been the subject of innumerable surveys for many decades. Dental treatment anxiety is a major obstacle in the path to an optimal oral health of the general population 2 4. People who suffer from DA have more tooth decay than others and take fewer preventive measures 5,6. The decay of the dentition can cause social isolation and even lead to the loss of a job or partner. The consequences may be mental, emotional and psychosomatic disorders 7,8. DA interferes with the patient s individual well-being and substantially affects his or her oral healthrelated quality of life (OHRQoL) 9. A study has shown that younger people are more afraid of dental treatment than older ones 10. Oral health, on the other hand, deteriorates with age 11. Then again, the relationship between DA and oral health becomes complex when assuming that impaired OHRQoL may cause higher levels of anxiety 6. The aim of the present observational study was to collect data on the prevalence of DA and its e290

2 Dental anxiety and OHRQoL in Switzerland e291 relationship to OHRQoL. It included new and consecutive patients seeking dental treatment at or being referred to a university clinic in Bern, Switzerland, specialising in prosthodontics and temporomandibular disorders. Therefore, the study presents a description of DA and OHRQoL for a very specific and interesting patient sample. It uses and compares two different measurement scales of DA and a region-adjusted profile for the assessment of OHRQoL. An evaluation of age- and genderspecific relationships is presented, explored and discussed. Methods Patients At the university department of prosthodontics, most patients seek or are referred to for treatment because of specific needs. All patients who were screened and admitted for treatment during a 6-month period between March and October 2007 were asked to participate in the study. They were either in need of prosthodontic treatment or had functional and temporomandibular joint (TMJ) problems. They were informed about the study and were required to fill in a questionnaire on a voluntary basis before any treatment was initiated. Only patients who signed an informed consent were included in the study. Overall, 236 such consents were returned. The response rate was high, and most patients agreed to take part in the study, possibly to shorten the waiting period in the anteroom. Exclusion criteria were an age below 20 or patients who were not able to understand the German questionnaire. Ethical approval for the study was obtained from the ethics committee of the faculty of medicine, University of Bern (KEK). Questionnaires To assess DA and OHRQoL, a single answer form was prepared which included three validated questionnaires, two related to DA and one to oral health. The Dental Anxiety Scale (DAS) by Corah was used as a measure of dental fear 12. It comprises four questions and a 5-scale answer to each question between 1 (no anxiety) and 5 (extreme anxiety), resulting in a range for the total score between 4 (no fear) and 20 (high fear). The reliability and validity of the DAS has been demonstrated in several previous studies 13,14. It was translated literally into a version in German from the original scale and validated 3. The Visual Analogue Scale of Dental Anxiety (VAS) was used as a graphic alternative to the prospective DAS questionnaire 15. It has a length of 100 mm with no fear at 0 mm and maximum imaginable fear at 100 mm, and its results can be allocated to three categories of low fear (<40 mm), moderate fear (40 70 mm) and high fear (>70 mm). A validation study in German was conducted by Barthelmes 16. To analyse whether and to what extent the results between the prospective DAS and the graphical VAS agreed, the Spearman s rank correlation coefficient was used. The Oral Health Impact Profile (OHIP) is the most widely used instrument today to measure OHRQoL of adults A region- and language-adjusted version was used in this study, namely the short OHIP in the German version with 14 items (OHIP- G14) 20,21. Therein, five answers, graded from never (0 points) to very often (4 points), are attributed to each question, resulting in a possible total score between 0 and 56 points where a high score means a low OHRQoL. OHIP-G14 expresses the extent to which the patient s oral health condition influences his or her well-being in the past month. Participants were given enough time in a quiet and neutral anteroom to complete all questions. Dental staff was instructed to provide help with the answer form if sought and needed. Statistical analysis The correct completion of the three individual parts of the answer form (DAS, VAS and OHIP-G14) was checked after participants returned them to dental staff. If one of the three parts was not filled in completely, that part was discarded. However, the remaining parts were considered for further statistical analyses that were independent from the missing part. For comparison, subgroups were formed, i.e. the answers were analysed in relation to gender and age. Six age groups were established, starting at the age of 20 with 10-year intervals up to 70+. The four levels of anxiety were defined, namely no fear at 4 points, low fear at 5 8, moderate fear at 9 14 and high fear at points, according to the DAS criteria for statistical analysis 14. Additionally, a distinction between highly anxious (DAS Score 15) and non-highly anxious participants (DAS < 15) was made. OHRQoL was rated as good if the OHIP-G14 score was less than the median score and as poor otherwise. The three parts of the answer form were compared in subgroups. The Wilcoxon rank-sum test

3 e292 V. Gisler et al. and the Kruskal Wallis test were applied (significance level a < 0.05). The correlations between the questionnaires were calculated using the Spearman s rank-sum correlation coefficient. Odds ratios and relative risk were calculated to compare the dependence between DA and OHRQoL. Owing to the small observation sample, exact Monte Carlo chi-squared test p-values were calculated. The computer software SAS 9.2 (2008, SAS Institute Inc., Cary, NC, USA) was used. Results Participants A total of 236 subjects returned the answer form and signed the informed consent. Thirteen of them were excluded from the analysis because of various missing data for key questions. Therefore, of a total 223 subjects, 111 women (49.8%) and 112 men (50.2%) were considered in the study. Of them, 78.9% were at or above the age of 50 (Fig. 1). The individual parts of the answer form were not completed with the same level of consistency: the OHIP-G14 showed the highest percentage of missing answers, followed by VAS and DAS. Therefore, sample sizes varied slightly in different analyses. A statistical description of the questionnaire scores is given in Table 1. Influence of gender and age Statistically, no influence of the subjects gender on the results of the questionnaires was found. A Wilcoxon rank-sum test of answers from men vs. women resulted in two-sided p-values of p VAS = 0.417, p DAS = 0.241, p OHIP-G14 = Therefore, the differentiation by the subjects gender was no longer used in the subsequent data evaluation. The subjects age did not have a statistically significant influence on any part of the answer form. A Kruskal Wallis test for the six age groups revealed that the subjects age was not significant to the total score for both anxiety and OHRQoL with p VAS = 0.412, p DAS = and p OHIP-G14 = Nevertheless, a quick analysis was carried out which showed that the highest scores, but also the highest standard deviations, were reached by the age group of with a mean DAS = 11.9 ± 4.37, a mean VAS = 46.0 ± 36.0 and a mean OHIP-G14 = 18.6 ± The oldest age group above the age of 70 showed a mean DAS = 9.79 ± 3.63, a mean VAS = 30.9 ± 31.6 and a mean OHIP-G14 = 14.9 ± Dental anxiety According to the four levels of the DAS classification, 3.29% reported no fear, 29.1% low, 52.1% moderate and 15.5% high fear (Table 2). The correlation between DAS and VAS was high with a Spearman s rank coefficient of The correlation between OHIP-G14 and DAS and between VAS and OHIP-G14 was and 0.312, respectively. This again demonstrates a good consistency between DAS and VAS. Figure 1 Distribution of age and gender in the total sample. OHRQoL The mean OHIP-G14 score was 16.0 ± 12.6 with a range from 0 to 51, a median value of 14 and a 90th percentile of 34 (Tables 1 and 2). An analysis of the 14 items is shown in Fig. 2, which lists the percentage of all items that were ticked off (a) as Questionnaire score N Mean SD Median Minimum Maximum Table 1 Overview of questionnaire scores for VAS, DAS and OHIP-G14. VAS ± DAS ± OHIP-G ± DAS, Dental Anxiety Scale; OHIP, Oral Health Impact Profile; VAS, Visual Analogue Scale.

4 Dental anxiety and OHRQoL in Switzerland e293 Table 2 Frequency counts of age as a function of DA measured by DAS and VAS and as a function of OHR- QoL measured by OHIP-G Total DAS Score VAS Length <40 mm mm mm OHIP-G14 Scores Min Quartile Median Quartile Max DA, dental anxiety; DAS, Dental Anxiety Scale; OHIP, Oral Health Impact Profile; OHRQoL, Oral health-related quality of life; VAS, Visual Analogue Scale. DAS Score: Fear categories vs. age groups: chi-squared test p-value = VAS Length: Fear categories vs. age groups: chi-squared test p-value = OHIP scores vs. age groups: Kruskal Wallis test p-value = Figure 2 OHIP-G14 items with distribution of often or very often and of all positive answers. positive and (b) as often/very often. For both (a) and (b), item 14 reached the highest response rate with 76.9 and 42.5%, respectively; item 10 had the lowest with 29.4 and 2.7%, respectively. Item 14 asks about the self-perception in relation to teeth, oral conditions and dental restorations. Item 10 expresses the complete inability to function. Dental anxiety and quality of life Table 3 illustrates the relation between OHRQoL and DA. Two subclasses were used, namely non-highly anxious (DAS score < 15) and highly anxious patients (DAS score 15). Similarly, the patients were allocated into two classes of either good OHRQoL (OHIP-G14 score < median) or poor OHRQoL (OHIP-G14 score median). A regression analysis was performed (Table 3) which shows a significant interdependence with p = The regression coefficient was calculated at r = The odds ratio was 3.55, which exhibits that highly anxious patients have a reduced OHRQoL. A further analysis regarding single items of OHIP-G14 and using the Spearman s rank correlation coefficient explained which items were most related to a subject s anxiety. These were item 3, related to the general quality of life, and item 5, standing for psychic tension, mental and emotional stress in the past month. Both items were correlated with VAS (r 3 = 0.34, r 5 = 0.35) and belonged to the four questions correlating best with DAS (r 3 = 0.25, r 5 = 0.33).

5 e294 V. Gisler et al. Table 3 Binary classification of patients into highly anxious and not highly anxious, with good or poor OHRQoL (top table) and binary logistic regression analysis of numbers (bottom table). OHRQoL Classification Poor (OHIP-G14 above median of 14) Good (OHIP-G14 below median of 14) Total Not-highly anxious (DAS 4 14) Highly anxious (DAS 15 20) Total Poor OHRQoL (1 = no below median, 0 = yes, median or above) Regression analysis Regression coefficient Standard error Odds ratio 95% Confidence interval p-value Highly anxious 0 = no, DAS = yes, DAS , DAS, Dental Anxiety Scale; OHIP, Oral Health Impact Profile; OHRQoL, Oral health-related quality of life. Frequency missing = 68. Discussion This study is the first analysis of the interdependency between DA and OHRQoL in a patient sample of Switzerland. It is a cross-sectional study including patients with specific needs, attending a university clinic specialised in prosthodontics and TMJ rehabilitation. Therefore, some bias must be assumed regarding the patient sample that cannot be considered representative for an average population. This may explain that 78.9% were at or above the age of 50. While the data were analysed related to age and gender, other factors like social class or income were not considered. Previous studies found them not to co-vary with DA 4,10,14. The answer form was completed quite well. The OHIP-G14 exhibited missing answers most often, probably due to the simple fact that OHIP-G14 items are relatively complex and unfamiliar. The DAS with only four questions was most often completed. The VAS requires little effort to complete; nevertheless, this visual and graphic method appeared to be an unusual task for some participants. General drawbacks of subjective surveys are the tendency of acquiescence and the fact that particularly men do not always give a sincere answer when they are asked about DA 22. The mean level of DA of 10.4 ± 3.89 identified by DAS complies with data from the relevant literature of other industrialised countries. With 15.5%, the fraction of highly anxious people is larger than the 5 10% reported in the literature 4,9,10,13,14,23,24. The 15.5% highly anxious people is a high percentage, considering that elderly patients feel less anxious than the general population 10,25. However, Hakeberg et al. 14 could show that individuals with high DA were more often patients at community dental clinics than at private clinics. VAS data were in good accordance with results from DAS. The correlation between the two anxiety scales was Therefore, the VAS scale might be a quick and useful tool for screening DA in the general practice. OHRQoL was measured with the OHIP-G14 and resulted in a mean value of 16.0 ± Data showed a skewedness, which appears to be characteristic for OHIP scores, with a median value of 14 and a 90th percentile of 34. Mehrstedt et al. 6 obtained a median of 1 and a 90th percentile of 13 for the general population in Germany. The less favourable median value in the present study stands for impaired OHRQoL. This may be explained by the patient sample with functional impairment, myofacial pain, prosthetic problems, missing teeth or edentulism. Interestingly, the oldest participants (age 70+) did not report the most impaired OHRQoL, but the age group of the years old did. A study found that subjects not seeking dental treatment and not wearing removable prostheses reached a standard OHIP- G14 reference median score of 0 points with a 90th percentile of 11. For patients with removable prostheses, the median was 4 with a 90th percentile of 17 and for patients with complete dentures, 6 with a 90th percentile of Therefore, the increased OHIP-G14 values in the present sample might be explained by increased DA.

6 Dental anxiety and OHRQoL in Switzerland e295 Gender differences were significant neither for anxiety measurements nor for the OHIP-G14. Regarding anxiety, women tend to report more frequently on higher DA than men; however, older men appear to be more ready to admit their DA than younger ones 10,25. Differences between age groups were not observed in the present study. The number of young patients was small, and their results showed a large standard deviation. The specific treatment needs of the patient sample in the present study probably had a higher impact on DAS, VAS and OHRQoL than gender and age. Bivariate analysis between DA and OHRQoL identified a significant association at p = The analysis compared high anxiety according to DAS with reduced OHRQoL as expressed by an OHIP-G14 value that was at or above the median. As such, this study differentiates between better and worse without making a quality judgment. An odds ratio of 3.55 showed that subjects with high DA were more likely to be among the patient group with a reduced OHRQoL. An analysis of the interdependence between oral health and the two anxiety scales based on specific questions produced a consistent picture. The OHIP- G14 items correlating most closely with the anxiety questionnaires were those about quality of life (item 3) and mental/emotional problems (item 5). Functional items of the OHIP (e.g. 9 or 10) were not strongly correlated with DAS and VAS. Positive answers to items questioning about the mental/ emotional disposition (such as items 5, 7 and 14) were frequently ticked off by anxious patients. This matches with McGrath and Bedi 9 who reported that there could be a number of reasons why DA and poor OHRQoL coexist in the same subgroup of the population. One reason is that both DA and perceived poor OHRQoL reflect psychological characteristics of the group and thus their related negative attitude. Both OHRQoL and DA are reported to be associated with psychological states 9. Another reason could be that dentally anxious people neglect their oral health to such an extent that they probably have high levels of untreated diseases. This may be pronounced for patients attending prosthodontic treatment at a special community clinic. This cross-sectional study, based on a specific patient sample in Switzerland, demonstrates that DA is associated with the impact that oral health has on quality of life. For epidemiological purposes and to obtain representative data for an average population of Switzerland, future studies must aim at including both types of subjects those seeking treatment and those not doing so. Representative telephone interviews would be a meaningful way to achieve this 4,27. References 1. Agras S, Sylvester D, Oliveau D. The epidemiology of common fears and phobias. Comprehens Psych 1969; 10: Milgrom P, Weinstein P. Dental fears in general practice: new guidelines for assessment and treatment. Int Dent J 1993; 43: Tönnies S, Mehrstedt M, Eisentraut I. Die Dental Anxiety Scale (DAS) und das Dental Fear Survey (DFS)- Zwei Messinstrumente zur Erfassung von Zahnbehandlungsängsten. Z Med Psychol 2002; 11: Milgrom P, Fiset L, Melnick S et al. The prevalence and practice management consequences of dental fear in a major US city. J Am Dent Assoc 1988; 116: Mehrstedt M, Tönnies S, Eisentraut I. Dental fears, health status and life quality. Anesth Prog 2004; 51: Mehrstedt M, John MT, Tönnies S et al. Oral health-related quality of life in patients with dental anxiety. Community Dent Oral Epidemiol 2007; 35: Portmann K, Radanov BP, Augustiny KF. Über den Zusammenhang zwischen Gebisszustand und Zahnarztangst. In: Psychotherapie, Psychosomatik und medizinische Psychologie 48. Stuttgart: Georg-Thieme- Verlag, 1998; Hakeberg M. Dental Anxiety and Health. Göteborg: University of Göteborg, Dissertation. 9. McGrath C, Bedi R. The association between dental anxiety and oral health-related quality of life in Britain. Community Dent Oral Epidemiol 2004; 32: Enkling N, Marwinski G, Jöhren P. Dental anxiety in a representative sample of residents of a large German city. Clin Oral Invest 2006; 10: Zitzmann NU, Staehelin K, Walls AW et al. Changes in oral health over a 10-yr period in Switzerland. Eur J Oral Sci 2008; 116: Corah NL. Development of a dental anxiety scale. J Dent Res 1969; 48: Corah NL, Gale EN, Illig SJ. Assessment of a dental anxiety scale. J Am Dent Assoc 1978; 97: Hakeberg M, Berggren U, Carlsson SG. Prevalence of dental anxiety in an adult population in a major urban area in Sweden. Community Dent Oral Epidemiol 1992; 20: Aitken RC. Measurement of feelings using visual analogue scales. Proc R Soc Med 1969; 62: Barthelmes M. Die visuelle Analogscala als Screening- Instrument zur initialen Diagnostik der Zahnbehandlungsangst: eine Validierungsstudie. Bern: University of Bern, Dissertation.

7 e296 V. Gisler et al. 17. Locker D, Allen F. What do measures of oral health-related quality of life measure? Community Dent Oral Epidemiol 2007; 35: Slade GD, Spencer AJ. Development and evaluation of the Oral Health Impact Profile. Community Dent Health 1994; 11: Slade GD. Derivation and validation of a short-form oral health impact profile. Community Dent Oral Epidemiol 1997; 25: John MT, Patrick DL, Slade GD. The German version of the Oral Health Impact Profile translation and psychometric properties. Eur J Oral Sci 2002; 110: John MT, Miglioretti DL, LeResche L et al. German short forms of the Oral Health Impact Profile. Community Dent Oral Epidemiol 2006; 34: Pierce KA, Kirkpatrick DR. Do men lie on fear surveys? Behav Res Ther 1992; 30: Eitner S, Wichmann M, Paulsen A et al. Dental anxiety an epidemiological study on its clinical correlation and effects on oral health. J Oral Rehabil 2006; 33: Locker D, Liddell AM. Correlates of dental anxiety among older adults. J Dent Res 1991; 70: Hagglin C, Berggren U, Hakeberg M et al. Variations in dental anxiety among middle-aged and elderly women in Sweden: a longitudinal study between 1968 and J Dent Res 1999; 78: John MT, Micheelis W, Biffar R. Normwerte mundgesundheitsbezogener Lebensqualität für Kurzversionen des Oral Health Impact Profile. Schweiz Monatsschr Zahnmed 2004; 114: Smith TA, Heaton LJ. Fear of dental care: are we making any progress? J Am Dent Assoc 2003; 134: Correspondence to: Dr Norbert Enkling, Department of Prosthodontics, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010 Bern, Switzerland. Tel.: +41 (0) Fax: +41 (0) norbert.enkling@zmk.unibe.ch