|
|
Volume 5: No.
2, April 2008
ORIGINAL RESEARCH
A New Brief Measure of Oral Quality of Life
Nancy R. Kressin, PhD, Judith A. Jones, DDS, MPH, Michelle B. Orner, MPH, Avron Spiro III, PhD
Suggested citation for this article: Kressin NR, Jones JA, Orner MB, Spiro A III. A new brief measure of oral quality of life. Prev Chronic Dis 2008;5(2). http://www.cdc.gov/pcd/issues/2008/
apr/06_0147.htm. Accessed [date].
PEER REVIEWED
Abstract
Introduction
We developed a brief measure of the impact of oral conditions on individual functioning and well-being, known as oral quality of life.
Methods
Among older male veterans (N = 827) and community dental patients (N = 113), we administered surveys consisting
of extant oral quality of life items, using clinical dental data from the veteran samples. We assigned each oral quality of life item to a theoretical dimension, conducted an iterative series of multitrait scaling analyses to examine the item-fit with the dimensions, reduced the number
of items, and examined the psychometric characteristics of new scales and their association with clinical indices.
Results
We developed two brief oral quality of life scales, one consisting of 12 items and
the other of 6, the latter a subset of the former. Each demonstrated sound psychometric properties and was sensitive to clinical indices.
Conclusion
The two brief oral quality of life scales can be used to assess the population-based impact of oral conditions as well as outcomes of dental care.
Back to top
Introduction
The individual and public health impact of dental disease is increasingly recognized (1). However, dentistry has traditionally used specific clinical indices (e.g., number of teeth, periodontal attachment loss) to assess the impact of dental conditions. The limitations of using such clinical
assessments of oral health status to understand the impact of oral disease are now clear (2): oral conditions
affect the full scope of health status, including patients’ functioning and well-being (e.g., oral quality of life [OQOL]) (3). Numerous patient-based measures of OQOL (4-8) have been developed, along with several clinician-based assessments (9-11). These measures vary in length (and, thus, ease of use in large-scale population-based surveys), in their sensitivity
to clinical indices (or changes therein), and in their theoretical anchoring. Few studies have simultaneously examined the performance of items from more than one instrument (12).
Our goal was to produce a brief measure of oral health-related quality of life that was theoretically anchored and psychometrically and clinically valid, using the best-performing items from existing instruments, to provide a public health tool
for assessing the individual and population impacts of oral health conditions.
Back to top
Methods
Samples
We studied two groups of older male veterans from the Veterans Health Study
and the Dental Longitudinal Study. The medical
and oral health status of these men covered a broad range of
conditions. We conducted a brief clinical oral exam (<15 minutes) and administered an oral health‑related quality of life questionnaire to men in each study. In addition, to test our new brief instrument, we collected new questionnaire data on a sample of community dental patients at the
time of a dental office visit.
1. The Veterans Health Study (VHS), begun in 1993, is a large-scale observational study (N = 2425) of veterans (mean age at the time of the study, 62
years), who are representative of independent, community-dwelling veterans who use Department of Veterans Affairs (VA) ambulatory care; as such, they had a variety of chronic medical conditions (13,14). A subset of 538 men completed the OQOL measures as part of an auxiliary study (15).
2. The Dental Longitudinal Study (DLS) is the dental component
consisting of 1231 participants from the VA Normative Aging Study (NAS), a closed‑panel longitudinal study of aging begun in 1968 among 2280 community-dwelling male veterans (mean age at the time of the study, 67
years) (16,17). The DLS is focused on oral health in aging men (18). Most are veterans but are not VA patients
and are generally representative of the adult male population in the greater Boston
metropolitan area, although
they may be healthier, because all subjects were required to be medically healthy for entry into the NAS. DLS participants receive clinical dental exams triennially and
were asked to complete an additional questionnaire concerning their oral quality of life; 289
participated.
3. Community dental patients who were
visiting one of 16 community dental offices for prophylaxis, endodontic care, or placement of a removable prosthesis were provided our OQOL survey; 113 patients,
both male and female, participated.
Data collection from each sample was approved by the local institution’s
institutional review board, and all participants gave written informed consent.
Theoretical framework
Our work was guided by a broad conceptualization of health and quality of life widely used in the general and oral health-related quality of life literature, which includes five broad domains (19-22):
- Survival is equated to mortality or longevity of the tooth or orofacial structures.
- Impairments and disease (or illness) include symptoms and indications of discomfort or pain.
- Functional states include three domains: a) physical functioning
(e.g., activity restrictions, difficulties eating, chewing, or speaking); b) social functioning
(e.g., the ability to perform social roles such as speaking, smiling, eating in public, being able to meet work and family obligations); and c) psychological functioning
(e.g., patient satisfaction with
the aesthetics of their dentition; comfort with interpersonal relations; worry, concern, embarrassment about, or lack of confidence
caused by problems with teeth or gums).
- Oral health perceptions include one’s global assessment of, and satisfaction with, oral health status and
aesthetics, including need for treatment.
- Finally, opportunity and resilience reflect disadvantages incurred as
a result of oral health and the impact of the disadvantages on one’s ability to function in social and work roles and to have good nutrition through a satisfactory ability to eat and chew.
We adapted this model to fit an oral/dental framework and then examined how well the adapted model fit our data on oral health and quality of life. We hypothesized a framework with four primary dimensions: 1) physical function, 2) psychosocial functioning (with three subdimensions: role function, distress, and worry), 3) impairment
or disease, and 4) perceptions.
Measures
The survey that we administered to our two veteran study populations included three extant OQOL measures (the Geriatric Oral Health Assessment Instrument, the Oral Health-Related Quality of Life
[OHQOL] measure, and the Oral Health Impact Profile) with a total of 64 OQOL items, concurrent with a clinical oral exam. The community dental patient sample received a survey
with an abbreviated selection of OQOL items but no clinical dental exam.
The Geriatric Oral Health Assessment Instrument (GOHAI) (5) comprises 12 items reflecting
3 domains of impact of oral disease: physical function, psychosocial function, and pain or discomfort.
The OHQOL measure is a brief global assessment of the impact of oral conditions on an individual’s functioning and well-being (4). The three OHQOL items assess the extent to which problems with teeth or gums influence an individual’s daily activities, social interactions, or avoidance of conversations.
Slade and Spencer (23) developed the Oral Health Impact Profile (OHIP), an empirically grounded 49-item instrument based on a conceptual framework of oral disease and its functional and psychosocial consequences. The OHIP contains seven subscales: 1) functional limitation, 2) pain, 3) psychological discomfort, 4) physical disability, 5) psychological disability, 6) social disability, and 7)
disadvantage.
Clinician‑assessed oral health status
We collected clinical data in the VHS and DLS. To assess periodontal
treatment need, we used the Community Periodontal Index of Treatment Need (CPITN) (24-26),
which is based on measures taken from 10 teeth from the 6 sextants of the mouth, yielding an index score (ordinal scale of 0–4). This index was developed by the World Health Organization as an efficient measure for use in epidemiologic
studies of periodontal status and treatment needs. Coronal caries and restorations were scored as in protocols of the National Institute of Dental Research for its National Survey of Oral Health in Adults (27), whereas root caries measures used an index developed by Hayes and Katz (28). This latter methodology, which has been used in two large epidemiologic studies, is efficient
because it requires assessment of root caries and restorations on only eight tooth surfaces instead of every tooth in the mouth (29,30).
Procedure and data analysis
First, three of the authors (NK, JJ, AS) independently categorized each item from the three OQOL instruments into one of the theoretical domains described above. Any differences in domain assignments were resolved by consensus. Next, using existing data from the two veteran samples (N = 827), we conducted a series of psychometric analyses and examined the fit of the items to the hypothesized
domains, using numerous iterations of multitrait scaling analysis (30,31), which is built on the logic of the multitrait-multimethod approach (32). Multitrait scaling analyses examine item-level characteristics (e.g., amount of missing data, frequency distribution, mean, standard deviation), the relationship of each item to other items in the scale that the item is hypothesized to measure, as
well as the item’s relationship to other scales. This analytic method provides information about scale distribution characteristics (e.g., mean, standard deviation, range, percentage of respondents scoring at the floor and ceiling) as well as the reliability of the scale scores and correlations among hypothesized scales. Compared with exploratory factor analysis, another commonly used
approach to scale development, multitrait scaling analyses take a more confirmatory approach, evaluating the appropriateness of a priori groupings of items, allowing the investigator to specify and analyze conceptually meaningful groups of items. Item internal consistency (the extent to which the item is related to the concept being measured) is considered acceptable if an item correlates 0.40 or
more with its hypothesized scale, after correction for item-scale overlap (30).
Item discriminant validity (the extent to which the item measures what it is supposed to measure) is considered acceptable if the correlation between the item and its hypothesized scale is significantly higher than the item’s correlation with all other scales (32); we used the significance level of two standard errors (95% confidence interval) for this criterion. For internal consistency
reliability (the extent to which items within a scale share common variance), we considered a Cronbach
α of .70 to be acceptable (33).
Multiple approaches may be used to produce short-form measures of health-related quality of life (15), including item impact studies, factor analytic approaches (described above), and stepwise regression analysis. We were unable to adopt an item impact approach because we did not have item impact data for two of the three measures we used, and our choice of the multitrait scaling analysis was
largely driven by our desire to confirm and refine our hypothesized conceptual schema.
Back to top
Results
On the basis of the initial multitrait scaling analyses, we identified
three items (GOHAI3, GOHAI5, GOHAI8) that correlated poorly with all of the domains we originally hypothesized, so we eliminated these items. We created a separate denture subscale, recognizing that denture functioning represents a conceptual dimension
separate from that of natural teeth; this also further improved scaling
properties. Results indicated that the psychosocial and opportunity items covered four dimensions:
1) distress, 2) self-consciousness and worry, 3) role function, and 4) opportunity. Because most of the items in the latter construct loaded more strongly on other scales and because of skepticism about the usefulness of opportunity as an oral health construct, we deleted these three items (OHIP29, OHIP45, OHIP47).
Thus, we were left with three remaining psychosocial constructs: distress, self-consciousness
and worry, and role function. Additional analyses found that some items had poor loadings on the hypothesized dimensions. Accordingly, we moved the perception items (OHIP44, OHIP3, GOHAI7) from the perception dimension into the worry dimension of psychosocial
items, where they had higher loadings.
We then examined the impairment items, using exploratory factor analysis, because of concerns
about the multidimensionality of this domain. Indeed, we found four subdimensions:
1) mouth pain, 2) flavor, digestion, and breath, 3) tooth pain, and 4) denture discomfort.
On the basis of these results, we retained all of these items but further altered our conceptual model to include
five dimensions: 1) physical function,
2) impairment and disease, and three dimensions of psychosocial function: 3) role function,
4) distress, and 5) worry (Appendix 1).
Using the remaining items, we standardized the item scores so that the mean of each variable was 50 and the standard deviation, 10. We scored the scales by taking the mean of all the items, after reversing the response categories where necessary so that higher scores indicated poorer oral quality of life. Thus, we created five scales to correspond with the above dimensions, a separate scale of
the three denture-related items, and a summary scale comprising all items.
To develop a shorter version of the measure, we used data from the two veteran samples analyzed together
to conduct forward stepwise regressions on each scale. This process allowed us to determine which items explained the most variance in each scale score. We selected items that explained
either 80% of the variance or the first five items, whichever was greater. This resulted in five scales, each with five items.
All of the scales had excellent internal consistency reliability, ranging from .78 (impairment) to .92 (distress), with the other scales also having excellent reliability
(Table 1).
Next, we examined the correlations of each scale with clinical indices
(Table 1). The strongest correlation observed was between physical function and number of teeth (r =
−0.38). Coronal caries was moderately associated with worry (r = 0.23) and impairment (r = 0.18), whereas periodontal status was moderately associated with physical function (r
= 0.21) and worry (r = 0.21). Root caries had the
smallest correlations overall with OQOL.
We also examined mean scores on each of the quality of life dimensions by scores on the CPITN
and found that individuals with greater treatment need had significantly worse OQOL
(Table 2).
We then examined the proportion of variance explained in each oral quality of life dimension among different subgroups based on number of teeth (not shown). The impairment, physical function, worry, and role function scales explained the least variance among patients with no teeth and the most among patients having 1 to 10 teeth. The patterns observed for the distress scale were different:
the most variance was explained among those with either no teeth or 1 to 10 teeth, with the least (but still 97% of the variance explained) among those with 11 to 24 teeth.
Next, we administered these five scales and the three denture-specific items to the sample of community dental patients. Using multitrait analysis, we sought to reduce the number of items further by eliminating items contributing least to each scale’s internal consistency reliability and retaining items that conceptually best represented the spirit of the subscale. We eliminated items
whose deletion least affected the internal consistency reliability of the scales (Cronbach
α), and at the same time, sought to retain the items that we considered, from a conceptual standpoint, best represented the spirit of the subscale. We did this on two levels. First, we developed one 12-item measure
(Appendix 2) that includes 3-item subscales for each of
3 scales in the psychosocial
dimension (distress, worry, and role) and single items assessing dimensions entitled physical, denture, and pain (Cronbach
α of the 12 items = .90). We also developed a second, briefer 6-item measure that includes single items assessing each dimension (distress, worry, role, physical, denture, pain) (Cronbach
α for the scale = .80).
We then took these two brief measures, refined on the community dental patient sample, and returned to our original data set of 827 veterans to examine the association of the two brief scales with clinical indices. Both summary scales
were significantly correlated overall with number of teeth (r =
−0.35 and −0.23, for the 6- and 12-item scales, respectively), coronal decay (r =
0.09 and 0.14),
periodontal status (r = 0.19 and 0.20), and root caries (r = 0.14 and
0.12) (Table
3). Most items were significantly correlated with number of teeth, coronal decay, and periodontal status, but fewer were significantly correlated with root caries. Most items were associated with periodontal treatment need
(Table 4).
Back to top
Discussion
We sought to develop a brief oral quality of life measure that is theoretically anchored, psychometrically sound, and clinically responsive from items comprising three existing OQOL indices,
and that can be used by public health researchers, practitioners, and policy makers to assess the impact of oral conditions on people’s functioning and well-being. We conducted extensive psychometric
analyses, reducing the original 64-item pool to a set of 25 items comprising 5 theoretically derived scales that demonstrate sound psychometric properties and associations in the expected directions with clinical indices. We further reduced the number of items to two brief scales (one with 12 items and one with 6 items) that maintained strong psychometric characteristics. Both scales were
sensitive to differences in clinical dental status, supporting their validity.
Taken together, the findings indicate that these new oral quality of life measures are sensitive to clinical indicators of oral health status, suggesting their usefulness in monitoring population health, for
making prevalence estimates, for monitoring secular trends in population changes,
and for studying the effects of public health interventions designed to prevent or reduce the effects of
oral disease. The associations we detected between the oral quality of life measure and clinical indices are similar to those of other published findings
(12,36).
The intermediate results of examining the properties of the five 5-item scales showed that each scale accounted for a suitably high proportion of the variance. Thus, we conclude that the conceptual domains are well represented by the items in each scale. Importantly, our results indicate that both short-form scales are also sensitive to differences in clinical status and would be feasible to use
in the clinical setting as an outcomes measure or in the general population to assess the impact of differing clinical status. The observed differences in internal consistency reliability suggest that the 6-item measure is appropriate for comparing groups of people, whereas the 12-item measure would be appropriate for assessing outcomes among individuals.
These results were limited by our partial reliance on cohorts of veterans who were older and all men, and who are thus not representative of the population as a whole.
However, this disadvantage was offset by the availability of a rich clinical data set on these cohorts. Furthermore, the absence of detailed sociodemographic data on the community dental sample limited our ability to examine
associations with these factors.
What value does this new brief OQOL instrument add to the literature, especially given that there are other OQOL instruments of similar length (e.g., OHIP14, GOHAI)?
Other authors have compared the performance of various OQOL measures in their entirety (e.g., the OHIP14 and the OIDP [36,37] or the GOHAI and OHIP14 [38]), but to our knowledge, none have evaluated the relative
performance of individual items from multiple OQOL measures. Our new measure has undergone extensive psychometric analysis and evaluation regarding its sensitivity to clinical indices and, although others have conducted similar types of analyses (36,38) using less detailed clinical data, the availability of extensive clinical dental data on our cohorts provides added confidence in this
measure’s sensitivity to differences in oral health status. Slade (38) examined the relative performance of the 49 original OHIP items and developed a 14-item short form of the OHIP. Two of the items in his short-form measure also are present in ours (finding it difficult to relax with oral problems and being totally unable to function because of oral problems), but several other OHIP items
in our measure did not survive his item-reduction process, and 12 items in his short-form measure did not survive our item-reduction efforts.
Efforts are under way to use these new measures among populations of dental patients (39), including evaluations of responsiveness to change in clinical status (40). Future research would also benefit from a comparison of the performance of this new brief measure to that of other OQOL measures of similar length, in multiple settings, including the community, as well as in private dental
offices, or as a treatment outcomes measure for use by dental insurers.
Back to top
Acknowledgments
This research was supported by a grant from the Delta Dental Plans Association, the National Institutes
of Health (NIH)/National Institute of Dental and Craniofacial Research,
grant number U54 DE14264-02, and
by grants from the U.S. Department of Veterans Affairs Health Services Research and Development Service (IIR
93.025 Judith A. Jones, Principal Investigator; HFP 91-012, Pantel Vokonas,
Principal Investigator; RCS 02-066-1,
Nancy R. Kressin, Principal Investigator), and supported in part by NIH grants U54 DE014264, K24 DE000419 (R. I. Garcia,
Principal Investigator), and K24 DE018211 (Judith A.
Jones, Principal Investigator).
The views in this article are those of the authors and do not necessarily
represent the views of the Department of Veterans Affairs or of the Delta
Dental Plans Association.
Back to top
Author Information
Corresponding Author: Nancy R. Kressin, PhD, Research Career Scientist, Center for Health Quality, Outcomes and Economic Research, 200 Springs Road, Building 70 (152), Bedford, MA 01730. Telephone: 781-687-2949; E-mail: nkressin@bu.edu.
Author Affiliations: Judith A. Jones, Boston University School of
Dental Medicine; Center for Health Quality, Outcomes and Economic Research, Veterans Administration Medical Center (VAMC), Bedford, Massachusetts. Michelle B. Orner, Center for Health Quality, Outcomes and Economic Research, VAMC, Bedford, Massachusetts. Avron Spiro III, Center for Health Quality, Outcomes and Economic
Research, VAMC, Bedford, Massachusetts; Normative Aging Study, Department of
Veterans Affairs; and Boston Healthcare System, Boston University Goldman School
of Dental Medicine, Boston University School of Public Health, Boston,
Massachusetts.
Back to top
References
- National Institute of Dental and Craniofacial Research. Oral health in
America: a report of the Surgeon General. Rockville (MD): U.S. Department of
Health and Human Services; 2000.
- Cohen L, Jago JD.
Toward the formulation of sociodental indicators. Int J Health Serv 1976;6(4):681-98.
- Kressin NR.
Symposium on self-reported assessments of oral health outcomes. Introduction. J Dent Educ 1996;60(6):485-7.
- Kressin N, Spiro A III, Bosse R, Garcia R, Kazis L.
Assessing oral health-related quality of life: findings from the Normative Aging Study. Med Care 1996;34(5):416-27.
- Atchison KA, Dolan TA.
Development of the Geriatric Oral Health Assessment Index. J Dent Educ 1990;54(11):680-7.
- Slade GD, Spencer AJ.
Development and evaluation of the Oral Health Impact Profile. Community Dent Health 1994;11(1):3-11.
- Leao A, Sheiham A.
The development of a socio-dental measure of dental impacts on daily living. Community Dent Health 1996;13(1):22-6.
- Slade GD, editor. Measuring oral
health and quality of life. Chapel Hill (NC): University of North Carolina,
Dental Ecology; 1997.
- Nikias MK, Sollecito WA, Fink R.
An oral health index based on ranking of oral status profiles by panels of dental professionals. J Pub Health Dent 1979;39(1):16-26.
- Marcus M, Koch AL.
A proposed index of oral health status: a practical application. J Am Dent Assoc 1983;107:729-33.
- Marcus M, Koch AL, Gershen JA.
Construction of a population index of adult oral health status derived from dentists’ preferences. J Public Health Dent 1983;43(4):284-94.
- Jones J, Kressin N, Spiro A III, Miller D, Kazis L, Garcia R.
Comparison of patient-based oral health outcome measures. Qual Life Res 2004;13(5):975-85.
- Kazis LE, Miller DR, Clark J, Skinner K, Lee A, Rogers W, et al.
Health related quality of life in VA patients: results from the Veterans Health Study. Arch Intern Med 1998;158:626-32.
- Miller DR, Skinner KM, Kazis LE.
Study design and sampling in the Veterans Health Study. J Ambul Care Manage 2004;27(2):166-79.
- Jones J, Kressin N, Spiro A III, Randall C, Miller D, Hayes C, et al.
Self-reported and clinical oral health in users of VA health care.
J Gerontol A Biol Sci Med Sci 2001;56(1):M55-62.
- Bell B, Rose CL, Damon A.
The Veterans Administration longitudinal study of healthy aging. Gerontologist 1966;6(4):179-84.
- Bosse R, Ekerdt DJ, Silbert JE. The Veterans Administration Normative Aging Study. In: Mednick SA, Harway M, Finello KM, editors. Handbook of
longitudinal research, Volume 2, teenage and adult cohorts. New York (NY): Praeger; 1984.
- Kapur KK, Glass RL, Loftus ER, Alman JE, Feller RP. The Veterans Administration longitudinal study of oral health and disease: methodology and preliminary findings. Int J Aging Hum Dev 1972;2:125-37.
- Patrick DL, Bergner M.
Measurement of health status in the 1990s. Annu Rev Public Health 1990;11:165-83.
- Patrick DL, Erickson P. Health status and health policy: quality of life in health care evaluation and resource allocation. New York
(NY): Oxford University Press; 1993.
- Gift HC, Atchison KA.
Oral health, health, and health-related quality of life. Med Care 1995;33(11 Suppl):NS57-77.
- Slade GD. The Oral Health Impact Profile. In: Slade GD, editor. Measuring oral health and quality of life. Chapel Hill (NC): University of North Carolina, Dental Ecology; 1997.
- Locker D, Slade G.
Association between clinical and subjective indicators of oral health status in an older adult population. Gerodontology 1994;11(2):108-14.
- Ainamo J, Barmes D, Beagrie G, Cutress T, Martin J, Sardo-Infirri J.
Development of the World Health Organization (WHO) Community Periodontal Index of Treatment Needs (CPITN). Int Dent J 1982;32(3):281-91.
- Feldman RS, Douglass CW, Loftus ER, Kapur KK, Chauncey HH.
Interexaminer agreement in the measurement of periodontal disease. J Periodontal Res 1982;17:80-9.
- Ressler LL, Feldman RS. CPITN: Correlation and predictive value with treatment, plan and therapy. J Dent Res 1992;71:199.
- The national survey of oral health in U.S. employed adults and seniors: 1985-1986.
NIH Publication No. 87-2868. Bethesda (MD): National Institute of Dental
Research; 1987.
- Hayes C, Katz RV. An abbreviated examination for assessing root caries prevalence. J
Dent Res 1992;71(Special Issue):250.
- Hays RD, Hayashi R. Beyond internal consistency reliability: rationale and user’s guide for multitrait analysis program on the microcomputer. Behav Res Methods Instrum Comput 1990;22(2):167-75.
- Hays RD, Hayashi T, Carson S, Ware J. The Multitrait Analysis Program (MAP) user’s guide. Santa Monica
(CA): The Rand Corporation; 1988.
- Campbell D, Fiske D.
Convergent and discriminant validation by the multitrait-multimethod matrix. Psychol Bull 1959;56(2):81-105.
- Nunnally M, Bernstein I. Psychometric theory. 3rd ed. New York (NY): McGraw-Hill; 1994.
- Jokovic A, Locker D, Guyatt G.
Short forms of the Child Perceptions Questionnaire for 11–14-year-old children (CPQ11-14): development and initial evaluation. Health Qual Life Outcomes 2006;4:4.
- Robinson PG, Gibson B, Khan FA, Birnbaum W.
Validity of two oral health related quality of life measures. Community Dent Oral Epidemiol 2003;31(2):90-9.
- Duncan DB. t Tests and intervals for comparisons
suggested by the data. Biometrics 1975; 31(2):339-59.
- Robinson P, Gibson B, Khan F, Birnbaum W.
A comparison of OHIP 14 and OIDP as interviews and questionnaires. Community Dent Health 2001;18(3):144-9.
- Locker D, Matear D, Stephens M, Lawrence H, Payne B.
Comparison of the GOHAI and OHIP-14 as measures of the oral health-related quality of life of the elderly. Community Dent Oral Epidemiol 2001;29(5):373-81.
- Slade GD.
Derivation and validation of a short-form oral health impact profile. Community Dent Oral Epidemiol 1997;25(4):284-90.
- Cunha-Cruz J, Hujoel P, Kressin NR.
Oral health-related
quality of life of periodontal patients. J Periodontal Res 2007;42(2):169-76.
- Wright W, Kressin NA, Jones JA. The use of outcome measures in dental education: the value of the OH-1 and DELTA. Paper presented at the 5th Joint Meeting of the Association of State and Territorial Dental Directors and the American Association of Public Health Dentistry; April 29, 2004; Los Angeles, California.
Back to top
|
|
Table 2. Meana Oral Quality of Life Scores by Varying Levels of Periodontal Disease Among Participants in the Veterans Health Study and
the Dental Longitudinal Study,
1993–1995 (N = 827)