The Population Study of Women in Gothenburg, Sweden, was initiated in 1968–69. It was a combined medical and dental examination. At the start of the study, the women were 38, 46, 50, 54 and 60
years of age. Subsequent surveys were made in 1980–81, 1992–93 and 2004–05, when new groups of women were invited with the same inclusion criteria as in the previous examinations to ensure representativeness. Detailed information on the sampling procedure has been published previously
], however, a systematic random sampling method was used with women being invited born on day 6, 12, 18 and 24. This study, with a cross-sectional design, included women in Gothenburg, aged 38 and 50
years old, from the survey in 2004–05 where data on SOC and OHIP is available. There were 500 participants (N
207 and N
293 38-year-olds and 50-year-olds, respectively) and 346 non-participants. The non-participants in 2004–05 had a lower income and were more often immigrants compared with the participants
Written informed consent was obtained from all participants. The study was approved by the Regional Ethical Review Board at the University of Gothenburg (Dnr 134–05).
The survey included a medical and a dental examination, and self-rated questionnaires including global questions concerning socio-economic status, oral health/function and dental care behaviour, and tests of oral health-related quality of life, sense of coherence and dental anxiety.
Sense of coherence was measured with the short version of the SOC questionnaire which consists of 13 items related to the three interrelated components of SOC; comprehensibility (five items), manageability (four items), and meaningfulness (four items)
]. Each item was scored on a scale from 1–7 points, giving a total range from 13 to 91 points for the SOC score. A higher score indicates a stronger sense of coherence.
Oral health-related quality of life was measured with the Swedish version
] of the Oral Health Impact Profile (OHIP-14) which consists of 14 items describing several dimensions of health-related quality of life in an oral health context
]. Each item was scored on a five-degree scale, from 1
never to 5
very often, indicating the degree or severity to which individuals perceive their oral conditions/symptoms and effects on life situations. The sum of scores ranges from 14 to 70. The frequency of scores from 1 to 2 (never to seldom) and 3 to 5 (sometimes to very often) were categorized per item into dichotomous variables (0 or 1) and then summed up for all 14 items, giving scores between 0 and 14, with 62.5% of the individuals scoring 0; i.e.
, having experienced no symptoms or dysfunction at all from their mouth/teeth. A decision was made to dichotomize at a cut-off level of two points; thus, individuals having a score of three or more for this new variable were considered as having problems. This OHIP-14 score was used as the dependent variable in the subsequent statistical analysis. This method of calculating the OHIP-14 score is similar to a method used previously by Savolainen et al.
Dental anxiety was measured using the Dental Fear Survey (DFS), which consists of 20 items covering anticipatory anxiety, physiological reactions and situational anxiety
]. Responses are scored from 1 (no anxiety) to 5 (high intensity of anxiety), giving a total score from 20 to 100. A DFS score of 60 or higher denotes dental anxiety
], and was used as the cut-off point in this study to detect dental anxiety.
Self-reported oral health was measured with a question where the participants rated their oral health as poor, moderate, good or very good. For the analysis, this variable was dichotomized into poor (poor and moderate) and good (good and very good) oral health. Also included were questions regarding self-reported oral hygiene, chewing ability, self-reported mouth dryness, esthetic aspects of oral status, self-reported susceptibility to caries and periodontitis, and dental visiting habits. These variables were measured on a 4- or 5-degree scale from low to high, but dichotomized (Table
). The question of regularity of dental care was dichotomized into regular (dental care at least every second year) and irregular (less often).
Descriptive statistics (proportion %) of self-reported oral health and dental visiting habits with regard to low and high oral health-related quality of life (OHRQL)
Marital status was given as not living together (living alone, unmarried, divorced, widowed or married but not living together), or living together (co-habiting, married or in partnership).
Social group was divided into three categories, based on the women's own occupation. This information was transformed according to Carlson’s standard occupation grouping system
]: low social group (skilled and unskilled workers), medium social group (small-scale employers, lower rank officials, foremen) and high social group (large-scale employers and high or intermediate rank officials).
Educational levels were based on years of school attendance and reported as: low (1–9
years), medium (10–12
years), and high level of education (≥13
Income was measured in thousands of Swedish kronor (SEK). It was then divided into 3 categories; low, medium and high, where low income corresponded to the lowest 20% and high income to the highest 20%.
The statistical analysis consisted of descriptive statistics and inference testing using the t
-test, the chi-square test, Fisher’s exact test, one-way analysis of variance and multiple logistic regressions using SPSS 19.0. A hierarchical regression modelling strategy was applied by first including socio-economic status (SES) variables, then checking how much variability was accounted for by dental anxiety and SOC, and at the last step, SES, dental anxiety, SOC, and self-reported oral health were included for the full model thereby examining the contribution of each specific measuring area of interest. The test statistic Nagelkerke was used to assess the model fit. The chosen level of significance was p
0.05. The number of individuals included in the analyses varied from 488 to 493 due to some missing answers in the questionnaires.