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1.  Perfluorocarbons enhance a T2*-based MRI technique for identifying the penumbra in a rat model of acute ischemic stroke 
Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T2* magnetic resonance imaging (MRI) combined with a T2*oxygen challenge (T2*OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O2, T2*OC-defined penumbra exhibits ongoing glucose metabolism and tissue recovery on reperfusion. However, potential limitations in translating this technique include a sinus artefact in human scans with delivery of 100% OC and relatively small signal changes. Here we investigate whether an oxygen-carrying perfluorocarbon (PFC) emulsion can enhance the sensitivity of the technique, enabling penumbra detection with lower levels of inspired oxygen. Stroke was induced in male Sprague-Dawley rats (n=17) with ischemic injury and perfusion deficit determined by diffusion and perfusion MRI, respectively. T2* signal change was measured in regions of interest (ROIs) located within ischemic core, T2*OC-defined penumbra and equivalent contralateral areas during 40% O2±prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T2* response to 40% O2 in T2*-defined penumbra (mean increase of 10.6±2.3% compared to 5.6±1.5% with 40% O2, P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T2*OC technique for identifying penumbra in acute stroke patients.
doi:10.1038/jcbfm.2013.86
PMCID: PMC3764387  PMID: 23801243
acute stroke; BOLD contrast; brain imaging; focal ischemia; MRI
2.  Tibial Metastasis from Muscle Invasive Bladder Carcinoma: An Unusual Site 
Current Urology  2014;7(3):160-162.
We report a case of a 61-year-old gentleman who presented with frank hematuria with associated weight loss and on-going left knee pain. Subsequent investigation revealed a muscle invasive bladder carcinoma with a related unusual bone metastasis. Though bone metastases form bladder carcinoma are common, frequent deposition sites include the spinal column and pelvis. This case report is to the best of our knowledge the first reported case of a tibial metastasis for relevant bladder carcinoma. Furthermore, we reviewed the literature, relevant diagnostic and management surrounding such occurrences.
doi:10.1159/000343556
PMCID: PMC4024504  PMID: 24917780
Bladder neoplasm; Carcinoma; Bone metastasis
3.  Self-rated dental health and dental insurance: modification by household income 
Background
Previous studies have reported that socioeconomically disadvantaged Australians have poorer self-rated dental health (SRDH), are less likely to be insured for dental services and are less likely to have regular dental visits than their more advantaged counterparts. However, less is known about the associations between dental insurance and SRDH. The aim of this study was to examine the associations between SRDH and dental insurance status and to test if the relationship was modified by household income.
Methods
A random sample of 3,000 adults aged 30–61 years was drawn from the Australian Electoral Roll and mailed a self-complete questionnaire. Analysis included dentate participants. Bivariate associations were assessed between SRDH and insurance stratified by household income group. A multiple variable model adjusting for covariates estimated prevalence ratios (PR) of having good to excellent SRDH and included an interaction term for insurance and household income group.
Results
The response rate was 39.1% (n = 1,093). More than half (53.9%) of the participants were insured and 72.5% had good to excellent SRDH. SRDH was associated with age group, brushing frequency, insurance status and income group. Amongst participants in the $40,000– < $80,000 income group, the insured had a higher proportion reporting good to excellent SRDH (80.8%) than the uninsured (66.5%); however, there was little difference in SRDH by insurance status for those in the $120,000+ income group. After adjusting for covariates, there was a significant interaction (p < 0.05) between having insurance and income; there was an association between insurance and SRDH for adults in the $40,000– < $80,000 income group, but not for adults in higher income groups.
Conclusions
For lower socio-economic groups being insured was associated with better SRDH, but there was no association for those in the highest income group. Insurance coverage may have the potential to improve dental health for low income groups.
doi:10.1186/1477-7525-12-67
PMCID: PMC4029830  PMID: 24886540
Self-rated dental health; Oral health; Dental insurance; Income
4.  Health-related quality of life and income-related social mobility in young adults 
Background
To assess the association of income-related social mobility between the age of 13 and 30 years on health-related quality of life among young adults.
Methods
In 1988-89 n = 7,673 South Australian school children aged 13 years were sampled with n = 4,604 children (60.0%) and n = 4,476 parents (58.3%) returning questionnaires. In 2005-06 n = 632 baseline study participants responded (43.0% of those traced and living in Adelaide).
Results
Multivariate regressions adjusting for sex, tooth brushing and smoking status at age 30 showed that compared to upwardly mobile persons social disadvantage was associated (p < 0.05) with more oral health impact (Coeff = 5.5), lower EQ-VAS health state (Coeff = -5.8), and worse satisfaction with life scores (Coeff = -3.5) at age 30 years, while downward mobility was also associated with lower satisfaction with life scores (Coeff = -1.3).
Conclusions
Stable income-related socioeconomic disadvantage was associated with more oral health impact, and lower health state and life satisfaction, while being downwardly mobile was associated with lower life satisfaction at age 30 years. Persons who were upwardly mobile were similar in health outcomes to stable advantaged persons.
doi:10.1186/1477-7525-12-52
PMCID: PMC3996105  PMID: 24735954
Life-course; Mobility; Young adults; OHIP; EQ-VAS; SWLS
5.  Age, period and cohort analysis of patient dental visits in Australia 
Background
Understanding dentists’ capacity to supply dental services over time is a key element in the process of planning for the future. The aim was to identify time trends and estimate age, period and cohort effects in patients’ visits supplied per dentist per year.
Methods
Mailed questionnaires were collected from a random sample of Australian private general practice dentists. The response rates were 73%, 75%, 74%, 71%, 76% and 67% in 1983, 1988, 1993, 1998, 2003 and 2009, respectively. The time trends in the mean number of patient visits supplied per dentist per year (PPY) was described by using a standard cohort table and age-period-cohort analyses applying a nested general linear regression models approach.
Results
The mean number of PPY decreased across most age groups of dentists over the time of study. The age-period model showed that younger dentists (20–29 years) and older dentists (65–74 and 80–84 years) had lower PPY than middle-aged dentists, and the age-cohort model showed higher PPY among earlier cohorts, and lower PPY among more recent cohorts.
Conclusion
The study found a period effect of declining PPY over the observation period. More recent cohorts of dentists provide lower numbers of PPY than earlier cohorts at similar ages, but the provision of PPY among these younger cohorts appeared to be stable as they moved into middle age.
doi:10.1186/1472-6963-14-13
PMCID: PMC3893375  PMID: 24410733
Age; Period; Cohort; Patient visits
6.  Crossed cerebellar diaschisis: insights into oxygen challenge MRI 
Hyperoxia during T2*-weighted magnetic resonance imaging (oxygen challenge imaging (OCI)) causes T2*-weighted signal change that is dependent on cerebral blood volume (CBV) and oxygen extraction fraction (OEF). Crossed cerebellar diaschisis (CCD), where CBV is reduced but OEF is maintained, may be used to understand the relative contributions of OEF and CBV to OCI results. In subjects with large hemispheric strokes, OCI showed reduced signal change in the contralesional cerebellum (P=0.027, n=12). This was associated with reduced CBV in contralesional cerebellum (P=0.039, n=9). CCD may be a useful model to determine the relative contribution of CBV to signal change measured by OCI.
doi:10.1038/jcbfm.2012.142
PMCID: PMC3519419  PMID: 23047271
diaschisis; magnetic resonance imaging; stroke
7.  Household income modifies the association of insurance and dental visiting 
Background
Dental insurance and income are positively associated with regular dental visiting. Higher income earners face fewer financial barriers to dental care, while dental insurance provides partial reimbursement. The aim was to explore whether household income has an effect on the relationship between insurance and visiting.
Methods
A random sample of adults aged 30–61 years living in Australia was drawn from the Electoral Roll. Data were collected by mailed survey in 2009–10, including age, sex, dental insurance status and household income.
Results
Responses were collected from n = 1,096 persons (response rate = 39.1%). Dental insurance was positively associated with regular visiting (adjusted prevalence ratio (PR) = 1.18; 95% CI: 1.01-1.36). Individuals in the lowest income tertile had a lower prevalence of regular visiting than those in the highest income group (PR = 0.78; 95% CI: 0.65-0.93). Visiting for a check-up was less prevalent among lower income earners (PR = 0.65; 95% CI: 0.50-0.83). Significant interaction terms indicated that the associations between insurance and visiting varied across income tertiles showing that income modified the effect.
Conclusions
Household income modified the relationships between insurance and regular visiting and visiting for a check-up, with dental insurance having a greater impact on visiting among lower income groups.
doi:10.1186/1472-6963-13-432
PMCID: PMC4015366  PMID: 24153023
Access; Dental visiting; Income; Insurance
8.  Trends in dental visiting avoidance due to cost in Australia, 1994 to 2010: an age-period-cohort analysis 
Background
The cost of dental care may be a barrier to regular dental attendance with the proportion of the Australian population avoiding or delaying care due to cost increasing since 1994. This paper explores the extent to which age, period and cohort factors have contributed to the variation in avoiding or delaying visiting a dentist because of cost.
Methods
Data were obtained from four national dental telephone interview surveys of Australian residents aged five years and over conducted in 1994, 1999, 2004 and 2010 (response rates 48% - 72%). The trend in the percentage of persons avoiding or delaying visiting a dentist because of cost was analysed by means of a standard cohort table and more formal age-period-cohort analyses using a nested models framework.
Results
There was an overall increase in the proportion of people avoiding or delaying visiting a dentist indicating the presence of period effects. Financial barriers were also associated with age such that the likelihood of avoiding because of cost was highest for those in their mid-late twenties and lowest in both children and older adults. Cohort effects were also present although the pattern of effects differed between cohorts.
Conclusion
The findings of this study suggest that, in addition to the increase in costs associated with dental care, policies targeting specific age groups and income levels may be contributing to the inequality in access to dental care.
doi:10.1186/1472-6963-13-381
PMCID: PMC3851774  PMID: 24090111
Age; Period; Cohort; Financial barriers; Dental; Access
9.  Development of a treatment optimism scale for HIV-positive gay and bisexual men 
AIDS care  2009;21(9):1090-1097.
Potential items to be included in an HIV Treatment Optimism scale were reviewed by 17 HIV-positive gay and bisexual men (GBM), resulting in a 21-item test instrument. After pilot testing, data were collected from a multi-city sample of high-risk HIV-positive GBM (n = 346), who were currently on treatment and were recruited to attend a two-day sexual health seminar. The scale items were analyzed utilizing Principal Components Analysis and reliability testing. The factor analysis resulted in the development of three separate scales. The Susceptibility scale contained 10 items associated with a belief that HIV is less transmissible while on HIV treatment. The Condom Motivation scale contained five items addressing a decreased motivation to use condoms while on treatment and the Severity scale contained four items associated with a decreased sense of the severity of an HIV diagnosis. Reliability coefficients (α ) and mean inter-item correlations (M) for the three scales were acceptable (Susceptibility, α = 0.86, M = 0.39; Condom Motivation, α = 0.84, M = 0.50; Severity, α = 0.71, M = 0.37). Combined as one scale, the reliability coefficient was respectable (α = 0.76), but the mean inter-item correlation was 0.14. Based on this analysis, use of a single measure was not supported and three separate scales were developed. The scales were equivalent across racial groups except White men were more like to report a decreased motivation to use condoms compared to Black or Latino men. Three separate scales addressing beliefs about the transmissibility of HIV while on treatment (Susceptibility), the quality of life while on HIV treatment (Severity) and the motivation to use condoms consistently while on treatment (Condom Motivation) may be better markers for assessing optimistic beliefs about HIV treatment among HIV-positive GBM.
doi:10.1080/09540120802705859
PMCID: PMC3698947  PMID: 20024767
HIV optimism; gay men; HIV; scale development
10.  HIV TREATMENT OPTIMISM AND UNSAFE ANAL INTERCOURSE AMONG HIV-POSITIVE MEN WHO HAVE SEX WITH MEN: FINDINGS FROM THE POSITIVE CONNECTIONS STUDY 
This study was designed to examine the impact of HIV treatment optimism on sexual risk among a racially diverse sample of HIV-positive MSM. Survey data were collected from 346 racially diverse HIV-positive MSM. Inclusion criteria: 18 years of age, male, at least one incident of unprotected anal intercourse (UAI) in the last year, currently on treatment. Other variables included demographics, sexual risk, depression, internalized homonegativity, HIV treatment history, alcohol/drug use and beliefs about HIV treatments (Susceptibility to transmit HIV, Severity of HIV infection and Condom Motivation). Those with lower income were more likely to report that HIV was less transmissible. A self-reported decrease in condom motivation was associated with being White, well-educated and increased alcoho/drug use. A decrease in Severity of HIV was associated with better mental health, being non-White and undetectable viral load. Sexual risk appears related to beliefs about how treatment affects the transmissibility of HIV. Race, socioeconomic status, alcoho/drug use, mental health and viral load were also associated with treatment beliefs.
doi:10.1521/aeap.2010.22.2.126
PMCID: PMC3698964  PMID: 20387983
11.  HIV Treatment Optimism and Sexual Risk Behaviors among HIV Positive African American Men who have Sex with Men 
The association between HIV treatment optimism—beliefs about susceptibility to transmit HIV, motivation to use condoms, and severity of HIV—and sexual risk behavior was examined among HIV-positive African American men who have sex with men (MSM). Participants were 174 men recruited in four major metropolitan areas of the United States to participate in a weekend HIV risk reduction intervention. Baseline results revealed that beliefs in less susceptibility to transmit HIV and less motivation to use condoms were significantly associated with more unprotected anal intercourse among serodiscordant casual partners. Less motivation to use condoms also predicted more unprotected insertive and receptive anal sex and was more important than susceptibility beliefs in predicting these behaviors. Suggestions are offered of ways to better inform HIV-positive African American MSM about their misperceptions about HIV treatment and how their level of optimism about HIV treatment may diminish or encourage condom use.
doi:10.1521/aeap.2012.24.2.91
PMCID: PMC3514953  PMID: 22468971
African American; HIV treatment optimism; condom use
12.  Assessment of the impact of the scanner-related factors on brain morphometry analysis with Brainvisa 
BMC Medical Imaging  2011;11:23.
Background
Brain morphometry is extensively used in cross-sectional studies. However, the difference in the estimated values of the morphometric measures between patients and healthy subjects may be small and hence overshadowed by the scanner-related variability, especially with multicentre and longitudinal studies. It is important therefore to investigate the variability and reliability of morphometric measurements between different scanners and different sessions of the same scanner.
Methods
We assessed the variability and reliability for the grey matter, white matter, cerebrospinal fluid and cerebral hemisphere volumes as well as the global sulcal index, sulcal surface and mean geodesic depth using Brainvisa. We used datasets obtained across multiple MR scanners at 1.5 T and 3 T from the same groups of 13 and 11 healthy volunteers, respectively. For each morphometric measure, we conducted ANOVA analysis and verified whether the estimated values were significantly different across different scanners or different sessions of the same scanner. The between-centre and between-visit reliabilities were estimated from their contribution to the total variance, using a random-effects ANOVA model. To estimate the main processes responsible for low reliability, the results of brain segmentation were compared to those obtained using FAST within FSL.
Results
In a considerable number of cases, the main effects of both centre and visit factors were found to be significant. Moreover, both between-centre and between-visit reliabilities ranged from poor to excellent for most morphometric measures. A comparison between segmentation using Brainvisa and FAST revealed that FAST improved the reliabilities for most cases, suggesting that morphometry could benefit from improving the bias correction. However, the results were still significantly different across different scanners or different visits.
Conclusions
Our results confirm that for morphometry analysis with the current version of Brainvisa using data from multicentre or longitudinal studies, the scanner-related variability must be taken into account and where possible should be corrected for. We also suggest providing some flexibility to Brainvisa for a step-by-step analysis of the robustness of this package in terms of reproducibility of the results by allowing the bias corrected images to be imported from other packages and bias correction step be skipped, for example.
doi:10.1186/1471-2342-11-23
PMCID: PMC3315423  PMID: 22189342
13.  Potential use of oxygen as a metabolic biosensor in combination with T2*-weighted MRI to define the ischemic penumbra 
We describe a novel magnetic resonance imaging technique for detecting metabolism indirectly through changes in oxyhemoglobin:deoxyhemoglobin ratios and T2* signal change during ‘oxygen challenge’ (OC, 5 mins 100% O2). During OC, T2* increase reflects O2 binding to deoxyhemoglobin, which is formed when metabolizing tissues take up oxygen. Here OC has been applied to identify tissue metabolism within the ischemic brain. Permanent middle cerebral artery occlusion was induced in rats. In series 1 scanning (n = 5), diffusion-weighted imaging (DWI) was performed, followed by echo-planar T2* acquired during OC and perfusion-weighted imaging (PWI, arterial spin labeling). Oxygen challenge induced a T2* signal increase of 1.8%, 3.7%, and 0.24% in the contralateral cortex, ipsilateral cortex within the PWI/DWI mismatch zone, and ischemic core, respectively. T2* and apparent diffusion coefficient (ADC) map coregistration revealed that the T2* signal increase extended into the ADC lesion (3.4%). In series 2 (n = 5), FLASH T2* and ADC maps coregistered with histology revealed a T2* signal increase of 4.9% in the histologically defined border zone (55% normal neuronal morphology, located within the ADC lesion boundary) compared with a 0.7% increase in the cortical ischemic core (92% neuronal ischemic cell change, core ADC lesion). Oxygen challenge has potential clinical utility and, by distinguishing metabolically active and inactive tissues within hypoperfused regions, could provide a more precise assessment of penumbra.
doi:10.1038/jcbfm.2008.56
PMCID: PMC3119432  PMID: 18545262
diffusion-weighted imaging; MCAO; oxygen challenge; rat brain; stroke; T2*
14.  Responsibility loadings for dental services by general dentists 
Background
Responsibility loadings determine relative value units of dental services that translate services into a common scale of work effort. The aims of this paper were to elicit responsibility loadings for a subset of dental services and to relate responsibility loadings to ratings of importance of the components of responsibility.
Methods
Responsibility loadings and ratings of components of responsibility were collected using mailed questionnaires from a random sample of Australian private general practice dentists in 2007 (response rate = 77%).
Results
Median responsibility loadings were 1.25 for an initial oral examination and for a 3+-surface amalgam restoration, 1.50 for a simple extraction and for root canal obturation (single canal), and 1.75 for subgingival curettage (per quadrant). Across the five services coefficients from a multivariate logit model showed that ratings of importance of knowledge (0.34), dexterity (0.24), physical effort (0.28) and mental effort (0.48) were associated with responsibility loadings (P < 0.05).
Conclusions
The elicited median responsibility loadings showed agreement with previous estimates indicating convergent validity. Components of responsibility were associated with loadings indicating that components can explain and predict responsibility aspects of dental service provision.
doi:10.1186/1472-6963-10-177
PMCID: PMC2906458  PMID: 20569457
15.  Prospective multi-centre Voxel Based Morphometry study employing scanner specific segmentations: Procedure development using CaliBrain structural MRI data 
Background
Structural Magnetic Resonance Imaging (sMRI) of the brain is employed in the assessment of a wide range of neuropsychiatric disorders. In order to improve statistical power in such studies it is desirable to pool scanning resources from multiple centres. The CaliBrain project was designed to provide for an assessment of scanner differences at three centres in Scotland, and to assess the practicality of pooling scans from multiple-centres.
Methods
We scanned healthy subjects twice on each of the 3 scanners in the CaliBrain project with T1-weighted sequences. The tissue classifier supplied within the Statistical Parametric Mapping (SPM5) application was used to map the grey and white tissue for each scan. We were thus able to assess within scanner variability and between scanner differences. We have sought to correct for between scanner differences by adjusting the probability mappings of tissue occupancy (tissue priors) used in SPM5 for tissue classification. The adjustment procedure resulted in separate sets of tissue priors being developed for each scanner and we refer to these as scanner specific priors.
Results
Voxel Based Morphometry (VBM) analyses and metric tests indicated that the use of scanner specific priors reduced tissue classification differences between scanners. However, the metric results also demonstrated that the between scanner differences were not reduced to the level of within scanner variability, the ideal for scanner harmonisation.
Conclusion
Our results indicate the development of scanner specific priors for SPM can assist in pooling of scan resources from different research centres. This can facilitate improvements in the statistical power of quantitative brain imaging studies.
doi:10.1186/1471-2342-9-8
PMCID: PMC2689209  PMID: 19445668
16.  Designing informative warning signals: Effects of indicator type, modality, and task demand on recognition speed and accuracy 
An experiment investigated the assumption that natural indicators which exploit existing learned associations between a signal and an event make more effective warnings than previously unlearned symbolic indicators. Signal modality (visual, auditory) and task demand (low, high) were also manipulated. Warning effectiveness was indexed by accuracy and reaction time (RT) recorded during training and dual task test phases. Thirty-six participants were trained to recognize 4 natural and 4 symbolic indicators, either visual or auditory, paired with critical incidents from an aviation context. As hypothesized, accuracy was greater and RT was faster in response to natural indicators during the training phase. This pattern of responding was upheld in test phase conditions with respect to accuracy but observed in RT only in test phase conditions involving high demand and the auditory modality. Using the experiment as a specific example, we argue for the importance of considering the cognitive contribution of the user (viz., prior learned associations) in the warning design process. Drawing on semiotics and cognitive psychology, we highlight the indexical nature of so-called auditory icons or natural indicators and argue that the cogniser is an indispensable element in the tripartite nature of signification.
doi:10.2478/v10053-008-0064-6
PMCID: PMC2865004  PMID: 20523852
auditory warnings; workload; modality; icons; semiotics
17.  Dental service patterns among private and public adult patients in Australia 
Background
While the majority of dental care in Australia is provided in the private sector those patients who attend for public care remain a public health focus due to their socioeconomic disadvantage. The aims of this study were to compare dental service profiles provided to patients at private and public clinics, controlling for age, sex, reason for visit and income.
Methods
Data were collected in 2004–06, using a three-stage, stratified clustered sample of Australians aged 15+ years, involving a computer-assisted telephone interview (CATI), oral examination and mailed questionnaire. Analysis was restricted to those who responded to the CATI.
Results
A total of 14,123 adults responded to the CATI (49% response) of whom 5,505 (44% of those interviewed) agreed to undergo an oral epidemiological examination. Multivariate analysis controlling for age, sex, reason for visit and income showed that persons attending public clinics had higher odds [Odds ratio, 95%CI] of extraction (1.69, 1.26–2.28), but lower odds of receiving oral prophylaxis (0.50, 0.38–0.66) and crown/bridge services (0.34, 0.13–0.91) compared to the reference category of private clinics.
Conclusion
Socio-economically disadvantaged persons who face barriers to accessing dental care in the private sector suffer further oral health disadvantage from a pattern of services received at public clinics that has more emphasis on extraction of teeth and less emphasis on preventive and maintenance care.
doi:10.1186/1472-6963-8-1
PMCID: PMC2246120  PMID: 18173837
18.  Positive and negative affect and oral health-related quality of life 
Background
The aims of the study were to assess the impact of both positive (PA) and negative affect (NA) on self-reported oral health-related quality of life and to determine the effect of including affectivity on the relationship between oral health-related quality of life and a set of explanatory variables consisting of oral health status, socio-economic status and dental visiting pattern.
Methods
A random sample of 45–54 year-olds from metropolitan Adelaide, South Australia was surveyed by mailed self-complete questionnaire during 2004–05 with up to four follow-up mailings of the questionnaire to non-respondents (n = 986 responded, response rate = 44.4%). Oral health-related quality of life was measured using OHIP-14 and affectivity using the Bradburn scale. Using OHIP-14 and subscales as the dependent variables, regression models were constructed first using oral health status, socio-economic characteristics and dental visit pattern and then adding PA and NA as independent variables, with nested models tested for change in R-squared values.
Results
PA and NA exhibited a negative correlation of -0.49 (P < 0.01). NA accounted for a larger percentage of variance in OHIP-14 scores (3.0% to 7.3%) than PA (1.4% to 4.6%). In models that included both PA and NA, PA accounted for 0.2% to 1.1% of variance in OHIP-14 scores compared to 1.8% to 3.9% for NA.
Conclusion
PA and NA both accounted for additional variance in quality of life scores, but did not substantially diminish the effect of established explanatory variables such as oral health status, socio-economic status and dental visit patterns.
doi:10.1186/1477-7525-4-83
PMCID: PMC1626449  PMID: 17052358
19.  Mapping oral health related quality of life to generic health state values 
Background
A summary utility index is useful for deriving quality-adjusted life years (QALY) for cost analyses or disability weights for burden of disease studies. However, many quality of life instruments provide descriptive profiles rather than a single utility index. Transforming quality of life instruments to a utility index could extend the use of quality of life instruments to costs analyses and burden of disease studies. The aims of the study were to map a specific oral health measure, the Oral Health Impact Profile to a generic health state measure, the EuroQol, in order to enable the estimation of health state values based on OHIP data.
Methods
Data were collected from patients treated by a random sample of South Australian dentists in 2001–02 using mailed self-complete questionnaires. Dentists recorded the diagnosis of dental conditions and provided patients with self-complete questionnaires to record the nature, severity and duration of symptoms using the EuroQol (EQ-5D) and 14-item version of the Oral Health Impact Profile (OHIP-14) instruments. Data were available from 375 patients (response rate = 72%). A random two-thirds sample of patients was used in tobit regressions of EQ-5D health state values estimated using OHIP-14 in a model with categories of OHIP responses as indicator variables and in a model with OHIP responses as continuous variables. Age and sex were included as covariates in both models. The remaining one-third sample of patients was used to test the models.
Results
The OHIP item 'painful aching in mouth' was significantly related to health state values in both models while 'life less satisfying' was also significant in the continuous model. Mean forecast errors relative to the mean observed health state value were higher when fitted to the categorical model (17.4%) compared to the continuous model (15.2%) (P < 0.05).
Conclusion
The findings enable health state values to be derived from OHIP-14 scores for populations where utility has not or cannot be measured directly.
doi:10.1186/1472-6963-6-96
PMCID: PMC1570134  PMID: 16893470
20.  Practice activity trends among oral and maxillofacial surgeons in Australia 
Background
The aim of this study was to describe practice activity trends among oral and maxillofacial surgeons in Australia over time.
Methods
All registered oral and maxillofacial surgeons in Australia were surveyed in 1990 and 2000 using mailed self-complete questionnaires.
Results
Data were available from 79 surgeons from 1990 (response rate = 73.8%) and 116 surgeons from 2000 (response rate = 65.1%). The rate of provision of services per visit changed over time with increased rates observed overall (from 1.43 ± 0.05 services per visit in 1990 to 1.66 ± 0.06 services per visit in 2000), reflecting increases in pathology and reconstructive surgery. No change over time was observed in the provision of services per year (4,521 ± 286 services per year in 1990 and 4,503 ± 367 services per year in 2000). Time devoted to work showed no significant change over time (1,682 ± 75 hours per year in 1990 and 1,681 ± 94 hours per year in 2000), while the number of visits per week declined (70 ± 4 visits per week in 1990 to 58 ± 4 visits per week in 2000).
Conclusions
The apparent stability in the volume of services provided per year reflected a counterbalancing of increased services provided per visit and a decrease in the number of visits supplied.
doi:10.1186/1472-6963-4-37
PMCID: PMC544360  PMID: 15613233
21.  Disability weights for the burden of oral disease in South Australia 
Background
Australian burden of disease estimates appeared inconsistent with the reported repetitive and ubiquitous nature of dental problems. The aims of the study were to measure the nature, severity and duration of symptoms for specific oral conditions, and calculate disability weights from these measures.
Methods
Data were collected in 2001–02 from a random sample of South Australian dentists using mailed self-complete questionnaires. Dentists recorded the diagnosis of dental problems and provided patients with self-complete questionnaires to record the nature, severity and duration of symptoms using the EuroQol instrument. Data were available from 378 dentists (response rate = 60%).
Results
Disability weights were highest for pulpal infection (0.069), caries (0.044) and dentinal sensitivity (0.040), followed by denture problems (0.026), periodontal disease (0.023), failed restorations (0.019), tooth fractures (0.014) and tooth wear (0.011). Aesthetic problems had a low disability weight (0.002), and both recall/maintenance care and oral hygiene had adjusted weights of zero.
Conclusions
Disability weights for caries (0.044), periodontal disease (0.023) and denture problems (0.026) in this study were higher than comparable oral health conditions in the Australian Burden of Disease and Injury Study (0.005 for caries involving a filling and 0.014 for caries involving an extraction, 0.007 for periodontal disease, and 0.004 for edentulism). A range of common problems such as pulpal infection, failed restorations and tooth fracture that were not included in the Australian Burden of Disease and Injury Study had relatively high disability weights. The inclusion of a fuller range of oral health problems along with revised disability weights would result in oral health accounting for a larger amount of disability than originally estimated.
doi:10.1186/1478-7954-2-7
PMCID: PMC517729  PMID: 15345059
Oral disease; Burden of disease; EuroQol; Disability weight
22.  Dimensions of oral health related quality of life measured by EQ-5D+ and OHIP-14 
Background
The aims of the study were to compare the dimensions of oral-health-related quality-of-life measured by a generic health state measure, the EuroQol, and a specific oral health measure, the Oral Health Impact Profile.
Methods
Data were collected in 2001–02 from a random sample of South Australian dentists using mailed self-complete questionnaires. Dentists recorded the diagnosis of dental problems and provided patients with self-complete questionnaires to record the nature, severity and duration of symptoms using the EuroQol (EQ-5D+) and 14-item version of the Oral Health Impact Profile (OHIP-14) instruments.
Results
Data were available from 375 patients (response rate = 72%). The EuroQol items of mobility, self care and usual activities formed a separate cluster of variables, as did anxiety/depression and cognition, while pain clustered with items from the OHIP physical pain subscale. OHIP items tended to form clusters consistent with the subscales of social disability, physical disability, physical pain, functional limitation and psychological discomfort. The OHIP handicap items clustered between the OHIP social disability and physical disability subscales. The OHIP psychological disability items split between the social disability and psychological discomfort subscales.
Conclusions
The observed clusters of variables empirically supported most of the conceptual dimensions of the OHIP. Both instruments covered symptom experience of pain indicating overlapping domains. However there was partial separation of the generic and specific items, EuroQol covered daily activities such as self-care and usual activities and OHIP covered oral health-specific aspects of functional limitation and physical disability as well as psychological and social aspects of disability and handicap.
doi:10.1186/1477-7525-2-35
PMCID: PMC479699  PMID: 15248893

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