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Quality of Life and Disability Weights Associated with Periodontal DiseaseAustralian Research Centre for Population Oral Health, School of Dentistry, The University of Adelaide, South Australia 5005 Correspondence: * corresponding author, david.brennan{at}adelaide.edu.au
Burden-of-oral-disease studies have been hampered by lack of data on disability weights. It is likely that disability weights will vary between conditions such as gingivitis and periodontal pockets. The aims of this study were to assess health-related quality of life and disability weights for periodontal conditions. A random sample of 45- to 54-year-olds was surveyed during 2004-05 (n = 879, response rate = 43.8%), with oral examinations on n = 709 persons (completion rate = 80.7%). Oral disease symptoms were recorded by the EuroQol, from which disability weights were calculated. Reported pain/discomfort ranged from 6.1% of persons (gingivitis) to 25.8% of persons (6+ mm pockets). Lower disability weights were associated with gingivitis (0.001) and 6+ mm gingival recession (0.004), with higher weights for 6+ mm loss of attachment (0.012) and 6+ mm pocket depth (0.018). Variation in symptom experience indicated the need for investigators to identify periodontal conditions and apply appropriate disability weights in burden-of-disease studies.
Key Words: quality of life • disability weights • periodontal disease
Although oral diseases are not usually life-threatening, they create a large burden. Dental problems have been ranked as the fourth most frequent illness condition (Spencer and Lewis, 1988), caries the highest-ranked diet-related disease (Crowley et al., 1992), and periodontal disease the fifth most prevalent health condition in Australia (AIHW, 2000). Periodontal diseases involve periodontal tissue inflammation that can be associated with gum recession or the formation of periodontal pockets. Pockets may lead to tooth mobility, formation of gum abscesses, and tooth loss (AIHW, 2002). Gingival bleeding has been reported to be highly prevalent throughout the world, with deep periodontal pockets affecting 10-15% of adults (Petersen and Ogawa, 2005). ’Disability-adjusted life years’ were developed for burden-of-disease studies and have been widely used for priority-setting (Murray et al., 1994; Anand and Hanson, 1997). However, oral health disability-adjusted life-year estimates in Australia have been hampered by the lack of recent oral disease data and disability weights. While oral health disability weights have been estimated for dental patients (Brennan and Spencer, 2004), these may overestimate disability compared with the population. An additional issue has been clinicians’ inability to differentiate between different types and levels of periodontal disease. The EuroQol is a generic instrument for describing and valuing health-related quality of life (Brooks, 1996), has been widely used, and has adequate validity (Bowling, 2001). The EuroQol provides a single number that represents an individual’s health status and preference value for that health state (Johnson and Coons, 1998). The EuroQol has been used in population surveys to establish population norms (Kind et al., 1998), and has been linked to the development of disability weights (Stouthard et al., 2000). The aims of this study were to identify symptom experience, health-related quality of life, and disability weights associated with a range of periodontal conditions in a random population sample.
Sampling and Data Collection A total of 2248 45- to 54-year-olds was randomly sampled from the electoral roll of Adelaide, South Australia. Sampled persons were surveyed by mailed questionnaire during 2004-05 by means of a primary approach letter, followed by the questionnaire (containing items such as socio-demographics, dental visiting, dental behavior, and oral impacts), then a reminder card and up to four follow-up mailings to non-respondents (Dillman, 1978). Questionnaire respondents were approached by telephone to participate in an oral examination, where clinical measures such as caries experience and periodontal disease were recorded based on standard criteria (NIDR, 1987). Informed consent was obtained prior to the examination. Following the examination, respondents were given a EuroQol questionnaire to record symptom experience associated with oral conditions diagnosed by the examining dentist.
Variables Measured After the oral examination, respondents were asked if the dental conditions had caused problems in each of six health-state dimensions, using the EuroQol (Brooks, 1996). The dimensions were: mobility (e.g., walking about), self-care (e.g., washing, dressing), usual activities (e.g., work, study, housework, family, or leisure), pain/discomfort, anxiety/depression, and cognition (e.g., memory, concentration, coherence, IQ). The EuroQol measures these dimensions on a three-level response: 1 (no problems), 2 (some/moderate problems), and 3 (extreme problems). The research was approved by the Human Research Ethics Committee of the University of Adelaide.
Analysis
Response In total, 879 persons responded (adjusted response rate = 43.8% after removal of out-of-scope persons). Oral examinations were performed on 709 persons (completion rate = 80.7%). Study participants generally showed a close approximation to the population profile (Table 1  ). Study participants had slightly fewer teeth, but no difference in denture-wearing, had a slightly lower percentage visiting the dentist in the preceding 12 months, slightly fewer visits in the preceding 12 months, and a lower percentage visiting privately (making a dental visit to a private dentist rather than a government-funded public clinic) at the last visit, but no difference in the percentage receiving check-ups at the last dental visit. There were no differences in the percentage of females, Australian-born, or Indigenous status, but study participants had a slightly higher percentage who spoke English as the main language at home, and a slightly higher percentage of concession card holders (government concession card holders generally comprise low-income groups such as the unemployed and aged pensioners), but there was no difference in the percentage from higher income households.
Symptom Experience Gingivitis was associated with a low prevalence of problems (6.1%) for pain/discomfort, which were experienced a low percentage of the time (17.5%) (Table 2 ). Gingival recession had a low prevalence of problems for pain/discomfort (11.1%) and anxiety/depression (11.1%), which were experienced for 30.1% and 1.0% of the time. Pocket depth of 6+ mm was associated with a low prevalence of problems for usual activities (3.2%) and anxiety/depression (9.7%) that were experienced 5.0% and 25.0% of the time. Prevalence of pain/discomfort was relatively higher (25.8%) and was experienced 49.4% of the time. Loss of attachment had a similar prevalence of problems for usual activities, pain/discomfort, and anxiety/depression, as observed for pocket depth of 6+ mm, but the percentage of time that problems associated with loss of attachment were experienced was lower for pain/discomfort (37.5%) and anxiety/depression (16.2%).
Symptoms were experienced for durations ranging from 297 wks for 6+ mm pocket depth to 489 wks for gingival recession (Table 3 ). Disability weights for periodontal conditions were low for gingivitis (0.001) and gingival recession (0.004). Relatively higher weights were observed for 6+ mm pocket depth (0.018) and 6+ mm loss of attachment (0.012). Similar relationships were observed for gingival recession when pocket depth was limited to less than or equal to 4 mm (0.002), and for pocket depth when gingival recession was limited to less than or equal to 4 mm (0.019).
Representativeness The yield (n = 879) provided sufficient numbers for analysis. However, the response rate was lower than anticipated, particularly with multiple follow-ups (Dillman, 1978). The electoral roll provided an adequate sampling frame for a population survey of adults. Generally, a response rate of 60% is considered adequate (Mangione, 1995), with lower response rates requiring evidence regarding bias. The issue is whether a lower response rate involves differential response. In this case, there was little evidence of response bias, with the main difference being the lower percentage of survey respondents who last visited privately.
Symptom Experience Duration was measured by reported amount of time since symptoms were first experienced or diagnosed. One can estimate the amount of symptomatic time by multiplying duration by the reported percentage of time problems were experienced. Since this was reported separately for each EuroQol dimension, and since pain was the most prevalent dimension reported, this might be used to adjust the reported duration to estimate the symptomatic time.
Disability Weights Cell sizes were small for gingival recession, so these findings must be interpreted cautiously. The relative standard error (standard error divided by mean) was 100% for the disability weights for gingival recession, compared with 39% and 42% for the weights for pocket depth, and 33% for loss of attachment. However, the reduction in disability weight for gingival recession, when pocket depth was restricted to less than or equal to 4 mm, and the increase in disability weight for pocket depth, when gingival recession was restricted to less than or equal to 4 mm, were consistent with the pocket depth contributing most to the disability weight for loss of attachment, and pocket depth and gingival recession contributing different levels, at the lower end of the range of possible disability weights.
Assumptions of Disability Weights Deriving disability weights for conditions with low impact can be difficult, especially if people have multiple conditions. However, burden of disease methodology requires separate estimation of conditions and, therefore, of disability weights, durations, and incidence. Some problems with differentiation of conditions can occur, but to some extent these can be overcome through measurement among those without multiple conditions, as we attempted through looking at disability weights of pocket depth where gingival recession was low. Generally, burden of disease methodology requires separate estimation of disability-adjusted life years for specific conditions at an aggregate population level, rather than combining them to estimate total disability weights across conditions within individuals. While the small numbers of cases and low precision of some estimates require cautious interpretation, the biologically plausible differentiation of disability weights by periodontal condition lends support to the findings. However, these require additional replication, with larger samples. Given the apparent differentiation in symptom experience, it is important that the conditions be estimated separately, particularly since surveys measure and report conditions in this way. Additional studies that can develop methodologies to measure durations more accurately would be valuable. Some of the variation in reported disability weights for periodontal disease in burden-of-disease studies could reflect assumptions made in the absence of empirical evidence on symptom experience of common oral health conditions, which the present study aims to address. Patient- and population-based estimates may differ, even for the same oral condition. It is possible that patients may have more severe symptoms that motivate them to visit a dentist, but this could be modified by treatment. ’Symptom icebergs’ are also possible, whereby people who are unable or unwilling to seek care may have a longer duration and severity of dental symptoms than patients. Analysis of Canadian population data showed that less than one in two who experienced oral and facial pain consulted a dentist or physician (Locker, 1988). Hence, further work to replicate the estimates in different populations, including patient- and population-based, will add to our evidence base on the burden of oral disease. Little symptom experience was associated with gingivitis and gingival recession, while relatively greater symptom experience was associated with periodontal pocket depth of 6+ mm. This indicates the need for correct identification of periodontal conditions and application of appropriate disability weights in burden-of-disease studies.
This study was funded by a National Health and Medical Research Council grant.
A supplemental appendix to this article is published electronically only at http://www.dentalresearch.org. Received for publication September 27, 2006. Revision received February 4, 2007. Accepted for publication April 17, 2007.
Journal of Dental Research, Vol. 86, No. 8,
713-717 (2007) This article has been cited by other articles:
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