Displaying publications 1 - 20 of 27 in total

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  1. Masood M, Reidpath DD
    Curr Med Res Opin, 2014 May;30(5):857-63.
    PMID: 24328497 DOI: 10.1185/03007995.2013.875466
    BACKGROUND: The aim of this paper was to review the types of approaches currently utilized in the analysis of multi-country survey data, specifically focusing on design and modeling issues with a focus on analyses of significant multi-country surveys published in 2010.
    METHODS: A systematic search strategy was used to identify the 10 multi-country surveys and the articles published from them in 2010. The surveys were selected to reflect diverse topics and foci; and provide an insight into analytic approaches across research themes. The search identified 159 articles appropriate for full text review and data extraction.
    RESULTS: The analyses adopted in the multi-country surveys can be broadly classified as: univariate/bivariate analyses, and multivariate/multivariable analyses. Multivariate/multivariable analyses may be further divided into design- and model-based analyses. Of the 159 articles reviewed, 129 articles used model-based analysis, 30 articles used design-based analyses. Similar patterns could be seen in all the individual surveys.
    CONCLUSION: While there is general agreement among survey statisticians that complex surveys are most appropriately analyzed using design-based analyses, most researchers continued to use the more common model-based approaches. Recent developments in design-based multi-level analysis may be one approach to include all the survey design characteristics. This is a relatively new area, however, and there remains statistical, as well as applied analytic research required. An important limitation of this study relates to the selection of the surveys used and the choice of year for the analysis, i.e., year 2010 only. There is, however, no strong reason to believe that analytic strategies have changed radically in the past few years, and 2010 provides a credible snapshot of current practice.
  2. Masood M, Reidpath DD
    BMJ Open, 2016 Jan 07;6(1):e008173.
    PMID: 26743697 DOI: 10.1136/bmjopen-2015-008173
    OBJECTIVES: Measuring the intraclass correlation coefficient (ICC) and design effect (DE) may help to modify the public health interventions for body mass index (BMI), physical activity and diet according to geographic targeting of interventions in different countries. The purpose of this study was to quantify the level of clustering and DE in BMI, physical activity and diet in 56 low-income, middle-income and high-income countries.
    DESIGN: Cross-sectional study design.
    SETTING: Multicountry national survey data.
    METHODS: The World Health Survey (WHS), 2003, data were used to examine clustering in BMI, physical activity in metabolic equivalent of task (MET) and diet in fruits and vegetables intake (FVI) from low-income, middle-income and high-income countries. Multistage sampling in the WHS used geographical clusters as primary sampling units (PSU). These PSUs were used as a clustering or grouping variable in this analysis. Multilevel intercept only regression models were used to calculate the ICC and DE for each country.
    RESULTS: The median ICC (0.039) and median DE (1.82) for BMI were low; however, FVI had a higher median ICC (0.189) and median DE (4.16). For MET, the median ICC was 0.141 and median DE was 4.59. In some countries, however, the ICC and DE for BMI were large. For instance, South Africa had the highest ICC (0.39) and DE (11.9) for BMI, whereas Uruguay had the highest ICC (0.434) for MET and Ethiopia had the highest ICC (0.471) for FVI.
    CONCLUSIONS: This study shows that across a wide range of countries, there was low area level clustering for BMI, whereas MET and FVI showed high area level clustering. These results suggested that the country level clustering effect should be considered in developing preventive approaches for BMI, as well as improving physical activity and healthy diets for each country.
    KEYWORDS: Body Mass Index (BMI); Intraclass correlation coefficient (ICC); Physical activity (METs)
    Study name: World Health Survey (Malaysia is a study site)
  3. Masood M, Masood Y, Newton T
    Caries Res, 2012;46(6):581-8.
    PMID: 23006794 DOI: 10.1159/000342170
    The aim of this study was to examine the impact that national income and income inequality in high and low income countries have on the relationship between dental caries and sugar consumption.
  4. Masood M, Reidpath DD
    PLoS One, 2017;12(6):e0178928.
    PMID: 28662041 DOI: 10.1371/journal.pone.0178928
    BACKGROUND: This study explores the relationship between BMI and national-wealth and the cross-level interaction effect of national-wealth and individual household-wealth using multilevel analysis.

    METHODS: Data from the World Health Survey conducted in 2002-2004, across 70 low-, middle- and high-income countries was used. Participants aged 18 years and over were selected using multistage, stratified cluster sampling. BMI was used as outcome variable. The potential determinants of individual-level BMI were participants' sex, age, marital-status, education, occupation, household-wealth and location(rural/urban) at the individual-level. The country-level factors used were average national income (GNI-PPP) and income inequality (Gini-index). A two-level random-intercepts and fixed-slopes model structure with individuals nested within countries was fitted, treating BMI as a continuous outcome.

    RESULTS: The weighted mean BMI and standard-error of the 206,266 people from 70-countries was 23.90 (4.84). All the low-income countries were below the 25.0 mean BMI level and most of the high-income countries were above. All wealthier quintiles of household-wealth had higher scores in BMI than lowest quintile. Each USD10000 increase in GNI-PPP was associated with a 0.4 unit increase in BMI. The Gini-index was not associated with BMI. All these variables explained 28.1% of country-level, 4.9% of individual-level and 7.7% of total variance in BMI. The cross-level interaction effect between GNI-PPP and household-wealth was significant. BMI increased as the GNI-PPP increased in first four quintiles of household-wealth. However, the BMI of the wealthiest people decreased as the GNI-PPP increased.

    CONCLUSION: Both individual-level and country-level factors made an independent contribution to the BMI of the people. Household-wealth and national-income had significant interaction effects.

  5. Masood M, Masood Y, Newton JT
    J Dent Res, 2015 Feb;94(2):281-8.
    PMID: 25421840 DOI: 10.1177/0022034514559408
    The objectives of this study were 1) to provide an estimate of the value of the intraclass correlation coefficient (ICC) for dental caries data at tooth and surface level, 2) to provide an estimate of the design effect (DE) to be used in the determination of sample size estimates for future dental surveys, and 3) to explore the usefulness of multilevel modeling of cross-sectional survey data by comparing the model estimates derived from multilevel and single-level models. Using data from the United Kingdom Adult Dental Health Survey 2009, the ICC and DE were calculated for surfaces within a tooth, teeth within the individual, and surfaces within the individual. Simple and multilevel logistic regression analysis was performed with the outcome variables carious tooth or surface. ICC estimated that 10% of the variance in surface caries is attributable to the individual level and 30% of the variance in surfaces caries is attributable to variation between teeth within individuals. When comparing multilevel with simple logistic models, β values were 4 to 5 times lower and the standard error 2 to 3 times lower in multilevel models. All the fit indices showed multilevel models were a better fit than simple models. The DE was 1.4 for the clustering of carious surfaces within teeth, 6.0 for carious teeth within an individual, and 38.0 for carious surfaces within the individual. The ICC for dental caries data was 0.21 (95% confidence interval [CI], 0.204-0.220) at the tooth level and 0.30 (95% CI, 0.284-0.305) at the surface level. The DE used for sample size calculation for future dental surveys will vary on the level of clustering, which is important in the analysis-the DE is greatest when exploring the clustering of surfaces within individuals. Failure to consider the effect of clustering on the design and analysis of epidemiological trials leads to an overestimation of the impact of interventions and the importance of risk factors in predicting caries outcome.
  6. Masood M, Masood Y, Newton T
    J Dent, 2014 Mar;42(3):249-55.
    PMID: 24373852 DOI: 10.1016/j.jdent.2013.12.004
    This study sought to assess the impact of posterior cross-bite on OHRQoL in young people aged 15-25 and to determine whether the impact on higher domains of Oral Health Impact Profile-14 (physical disability, psychological disability, social disability and handicap) is a direct function of the cross-bite or mediated through the lower domains of OHIP-14 (functional limitation, pain and discomfort).
  7. Bakri NN, Tsakos G, Masood M
    Br Dent J, 2018 07 27;225(2):153-158.
    PMID: 30050198 DOI: 10.1038/sj.bdj.2018.529
    Objective: The primary objective of this study was to examine the association between smoking and oral health-related quality of life (OHRQoL) among dentate people aged 16 years and above in England.
    Methods: Cross-sectional study, based on the Adult Dental Health Survey (ADHS) 2009. ADHS 2009 involved data collection from 11,380 face-to-face interviews and 6,469 dental examinations from England, Wales and Northern Ireland. This study focuses on the dentate sample from England, consisting of 5,622 individuals who underwent dental examination. OHRQoL was measured by two indices; Oral Health Impact Profile-14 (OHIP-14) and Oral Impacts on Daily Performance (OIDP). Unadjusted and adjusted zero-inflated regression models were used. Adjustment was sequentially done for socio-demographics, clinical oral conditions and self-reported general health.
    Results: Prevalence of those who had never smoked, past smokers and current smokers were 45.6%, 35.3% and 19.2% respectively. Current smokers had considerably higher mean OHIP-14 and OIDP scores than non-smokers. There was a statistically significant association between smoking and OHRQoL (both OHIP-14 and OIDP) even in the fully adjusted models. Current smokers were more likely to report worse OHRQoL compared to those who had never smoked in both OHIP-14 and OIDP score. There was no statistically significant difference between past smokers with those who had never smoked in reporting OHIP-14 and OIDP. Among those reporting OHRQoL, there was a stepwise gradient risk of reporting no oral impact, where the probability was higher among those who had never smoked, followed by past smokers and current smokers both in OHIP-14 and OIDP.
    Conclusion: Smoking was independently associated with worse OHRQoL, even after adjusting for a range of socio-demographic factors, clinical oral conditions and self-reported general health.
  8. Masood M, Masood Y, Newton T, Lahti S
    Angle Orthod, 2015 Nov;85(6):1057-63.
    PMID: 25535775 DOI: 10.2319/081514-575.1
    OBJECTIVES: To provide an empirical test of the applicability of Locker's conceptual model of oral health for malocclusion patients, and to suggest alternative models of the effect of malocclusion on well-being.
    MATERIALS AND METHODS: Data from a survey of 323 adolescents attending for orthodontic treatment were analyzed to develop a new oral health model for malocclusion patients. Oral health-related quality of life (OHRQoL) was measured using the 14-item Oral Health Impact Profile; malocclusion was measured using the Dental Health Component (DHC) of the Index of Orthodontic Treatment Need (IOTN). Using structural equation modeling, the relationship between conceptual domains in Locker's model was explored and three models of their interrelationship tested for goodness of fit.
    RESULTS: Fit indexes for Locker's model indicated that it did not fit the data well. Therefore, a modified model was developed to incorporate additional paths between other levels to better fit the data. The best fit was provided by a model in which the direct effects of malocclusion on pain, discomfort, and handicapping-and the direct effect of pain on disability-were removed. A direct effect of functional limitation on disability was allowed. The modified Oral Health Impact Profile model proved to be a good fit to the data (root mean square error of approximation  =  0.069).
    CONCLUSION: The pathways identified in Locker's (1988) conceptual model of oral health may not be appropriate for describing the relationships between OHRQoL constructs in individuals with malocclusion. An alternative model is proposed.
    KEYWORDS: Malocclusion; Oral Health Impact Profile; Oral health–related quality of life
  9. Reidpath DD, Masood M, Allotey P
    Int J Public Health, 2014 Jun;59(3):503-7.
    PMID: 24045784 DOI: 10.1007/s00038-013-0510-1
    OBJECTIVES: Four metrics to characterise population overweight are described.

    METHODS: Behavioural Risk Factors Surveillance System data were used to estimate the weight the US population needed to lose to achieve a BMI 

  10. Masood M, Masood Y, Newton TJ
    Dent Update, 2010 Jun;37(5):326-8, 331-2, 334-6.
    PMID: 20669712 DOI: 10.12968/denu.2010.37.5.326
    Over the last decade, researchers in health services research started using qualitative research methods. This has led to a corresponding rise in the reporting of the qualitative research studies in medical and related journals, including dental journals. Qualitative research is often contrasted with quantitative research as a set of 'non quantitative methods', since it does not deal with numbers and enumerate phenomena. It interprets the information people bring to research, which helps us to understand social phenomena in natural settings like their own territory, in their own language and on their own terms, giving emphasis to the meaning, experience and view of all the participants.

    CLINICAL RELEVANCE: This article will help the clinician to understand the importance of in-depth knowledge of behaviour and social phenomena around the patient.
  11. Masood M, Sheiham A, Bernabé E
    PLoS One, 2015;10(4):e0123075.
    PMID: 25923691 DOI: 10.1371/journal.pone.0123075
    This study assessed the extent of household catastrophic expenditure in dental health care and its possible determinants in 41 low and middle income countries. Data from 182,007 respondents aged 18 years and over (69,315 in 18 low income countries, 59,645 in 15 lower middle income countries and 53,047 in 8 upper middle income countries) who participated in the WHO World Health Survey (WHS) were analyzed. Expenditure in dental health care was defined as catastrophic if it was equal to or higher than 40% of the household capacity to pay. A number of individual and country-level factors were assessed as potential determinants of catastrophic dental health expenditure (CDHE) in multilevel logistic regression with individuals nested within countries. Up to 7% of households in low and middle income countries faced CDHE in the last 4 weeks. This proportion rose up to 35% among households that incurred some dental health expenditure within the same period. The multilevel model showed that wealthier, urban and larger households and more economically developed countries had higher odds of facing CDHE. The results of this study show that payments for dental health care can be a considerable burden on households, to the extent of preventing expenditure on basic necessities. They also help characterize households more likely to incur catastrophic expenditure on dental health care. Alternative health care financing strategies and policies targeted to improve fairness in financial contribution are urgently required in low and middle income countries.
    Study name: World Health Survey (Malaysia is a study site)
  12. Masood M, Aggarwal A, Reidpath DD
    BMC Public Health, 2019 Sep 03;19(1):1212.
    PMID: 31481044 DOI: 10.1186/s12889-019-7536-0
    BACKGROUND: To investigate the association between national culture and national BMI in 53 low-middle- and high-income countries.

    METHODS: Data from World Health Survey conducted in 2002-2004 in low-middle- and high-income countries were used. Participants aged 18 years and over were selected using multistage, stratified cluster sampling. BMI was used as an outcome variable. Culture of the countries was measured using Hofstede's cultural dimensions: Uncertainty avoidance, individualism, Power Distance and masculinity. The potential determinants of individual-level BMI were participants' sex, age, marital status, education, occupation as well as household-wealth and location (rural/urban) at the individual-level. The country-level factors used were average national income (GNI-PPP), income inequality (Gini-index) and Hofstede's cultural dimensions. A two-level random-intercepts and fixed-slopes model structure with individuals nested within countries were fitted, treating BMI as a continuous outcome variable.

    RESULTS: A sample of 156,192 people from 53 countries was included in this analysis. The design-based (weighted) mean BMI (SE) in these 53 countries was 23.95(0.08). Uncertainty avoidance (UAI) and individualism (IDV) were significantly associated with BMI, showing that people in more individualistic or high uncertainty avoidance countries had higher BMI than collectivist or low uncertainty avoidance ones. This model explained that one unit increase in UAI or IDV was associated with 0.03 unit increase in BMI. Power distance and masculinity were not associated with BMI of the people. National level Income was also significantly associated with individual-level BMI.

    CONCLUSION: National culture has a substantial association with BMI of the individuals in the country. This association is important for understanding the pattern of obesity or overweight across different cultures and countries. It is also important to recognise the importance of the association of culture and BMI in developing public health interventions to reduce obesity or overweight.

  13. Khuder T, Yunus N, Sulaiman E, Ibrahim N, Khalid T, Masood M
    J Oral Rehabil, 2017 May;44(5):398-404.
    PMID: 28295492 DOI: 10.1111/joor.12504
    This study aimed to investigate residual ridge resorption (RRR) of anterior and posterior maxillary and mandibular edentulous ridges, in patients treated with mandibular implant overdentures (IOD) and compare with conventional complete denture (CD) wearers, and to determine at each location, the association of RRR with the occlusal forces distribution and other patients' variables. The anterior and posterior RRR of IOD (six males, 17 females) and CD (12 males, 11 females) groups were determined using baseline and follow-up dental panaromic radiographs (DPT) (mean intervals 4 ± 1·8 years). The bone ratios were calculated using proportional area: anatomic to fixed reference areas and mean difference of ratios between the intervals determined RRR. The ridge locations included anterior and posterior maxillary and posterior mandibular arches. The T-Scan III digital occlusal system was used to record anterior and posterior percentage occlusal force (%OF) distributions. There were significant differences in anterior and posterior %OF between treatment groups. Two-way anova showed RRR was significant for arch locations (P = 0·005), treatment group (IOD versus CD) (P = 0·001), however, no significant interaction (P = 0·799). Multivariate regression analyses showed significant association between RRR and %OF at anterior maxilla (P = 0·000) and posterior mandible (P = 0·023) and for treatment groups at posterior maxilla (P = 0·033) and mandibular areas (P = 0·021). Resorption was observed in IOD compared to CD groups, with 8·5% chance of less resorption in former and 7·8% in the latter location. Depending on arch location, ridge resorption at various locations was associated with occlusal force distribution and/or treatment groups (implant prostheses or conventional complete dentures).
  14. Masood M, Masood Y, Reidpath DD, Newton T
    Lancet, 2014 Jun 14;383(9934):2046.
    PMID: 24931691 DOI: 10.1016/S0140-6736(14)60996-X
  15. Masood M, Masood Y, Saub R, Newton JT
    J Public Health Dent, 2014;74(1):13-20.
    PMID: 22994869 DOI: 10.1111/j.1752-7325.2012.00374.x
    Demand and use for oral health-related quality of life (OHRQoL) instruments have increased in recent years in both research and clinical settings. These instruments can be used to measure patient's health status or detect changes in a patient's health status in response to an intervention or changes in disease trajectory. Ensuring universal acceptance of these measures requires easy interpretation of its scores for clinicians, researchers, and patients. The most important way of describing and interpreting this significance of changes in OHRQoL is through the establishment of minimal important difference (MID). The minimally important difference represents the smallest improvement considered worthwhile by a patient. A comprehensive search of published literature identified only 12 published articles on establishment of MID for OHRQoL measures. This scarcity of published studies on MID encourages the need of appropriate interpretation and describing patient satisfaction in reference to that treatment using MID. Anchor- and distribution-based methods are the two general approaches that have been proposed and recommended to interpret differences or changes in OHRQoL. Both of these methods of determining the MID have specific shortcomings; therefore, it is proposed to adopt triangulation approaches in which the methods are combined. The objective of this review is to summarize the need for, importance of, and recommendations for methods of establishing MID for OHRQoL measures.
  16. Masood M, Thaliath ET, Bower EJ, Newton JT
    Community Dent Oral Epidemiol, 2011 Jun;39(3):193-203.
    PMID: 21070318 DOI: 10.1111/j.1600-0528.2010.00584.x
    To appraise the quality of published qualitative research in dentistry and identify aspects of quality, which require attention in future research.
  17. Masood M, Yusof N, Hassan MI, Jaafar N
    BMC Public Health, 2012;12:989.
    PMID: 23158416 DOI: 10.1186/1471-2458-12-989
    This was a retrospective cohort study undertaken to assess the rate and pattern of dental caries development in 6-year-old school children followed-up for a period of 5 years, and to identify baseline risk factors that were associated with 5 years caries experience in Malaysian children.
  18. Khalid T, Yunus N, Ibrahim N, Elkezza A, Masood M
    Clin Oral Implants Res, 2017 May;28(5):535-542.
    PMID: 26989853 DOI: 10.1111/clr.12831
    OBJECTIVE: To determine oral health-related quality of life (OHRQoL) and denture satisfaction (DS) in patients provided with mandibular implant-supported overdentures (ISOD) retained by two different attachment types, and the association of mandibular bone volume with the change in patient-reported outcome, before and after implant treatment.

    MATERIAL AND METHODS: Thirty-four patients (mean age 60.70  ±  8.7 years) received telescopic crown or locator attachments for ISOD and completed OHIP-14 (Malaysian version) and DS questionnaires, at baseline (T0 ) with new conventional complete dentures (CCD) and 3 months (T1 ) and 3 years (T2 ) after ISOD conversion. Mandibular bone volume was calculated from cone beam computed tomography (CBCT) datasets using Mimics software. Mean changes (MC) in OHIP-14 and DS at intervals were analyzed using the Wilcoxon signed-rank test and effect size (ES). The association of bone volume, implant attachment type, and other patient variables with the change in OHIP-14 and DS were determined using multivariate linear regression analysis.

    RESULTS: The MC in OHIP-14 and DS scores from T0 to T1 and T2 showed significant improvement with moderate and large ES, respectively. Regression analyses for the change in OHIP-14 score from T0 to T2 showed significant association with implant attachment type (P = 0.043), bone volume (P = 0.004), and baseline OHIP-14 (P = 0.001), while for DS, the association was only significant with baseline DS score (P = 0.001).

    CONCLUSION: Improvement in patients' OHRQoL and satisfaction with ISOD was associated with their baseline ratings. Mandibular bone volume had a stronger association for improvement in OHRQoL compared to type of attachment.

  19. Masood M, Younis LT, Masood Y, Bakri NN, Christian B
    J Clin Periodontol, 2019 02;46(2):170-180.
    PMID: 30657192 DOI: 10.1111/jcpe.13072
    OBJECTIVES: The aim of this study was to investigate the impact of periodontal disease on the domains of oral health-related quality of life (OHRQoL) of United Kingdom adults.

    METHODS: National representative data from the 2009 Adult Dental Health Survey, United Kingdom, were used in this study. Periodontal disease severity was measured using periodontal pocket depth and categorized into three groups: pocket depth up to 3.5, 3.5-5.5 and more than 5.5 mm. OHRQoL was measured using the Oral Health Impact Profile-14 (OHIP-14) scores. Bivariate and multivariable Zero-inflated Poisson regression analysis was used.

    RESULTS: A total of 6378 participants was analysed in this study. Periodontal pocketing was significantly associated with higher OHIP-14 scores. Participants with periodontal pocket depths >3.5 mm had a significantly higher prevalence for functional limitation, physical pain and social disability than participants with pocket depths of less than 3.5 mm. Participants with periodontal pocket depth(s) >5.5 mm had significantly higher OFOVO prevalence in all the domains of OHIP-14 except handicap domain than participants with pocket depth(s) <3.5 mm.

    PARTICIPANTS:

    CONCLUSION: This study showed that for a nationally representative sample of the United Kingdom population, periodontal disease was significantly associated with the domains of OHRQoL.

  20. Masood M, Newton T, Bakri NN, Khalid T, Masood Y
    J Dent, 2017 Jan;56:78-83.
    PMID: 27825838 DOI: 10.1016/j.jdent.2016.11.002
    OBJECTIVES: To identify the determinants of OHRQoL among older people in the United Kingdom.

    METHODS: A subset of elderly (≥65year) participants from the UK Adult Dental Health Survey 2009 data was used. OHRQoL was assessed by means of the OHIP-14 additive score. The number of missing teeth; presence of active caries, dental pain, root caries, tooth wear, periodontal pockets>4mm, loss of attachment>9mm; having PUFA>0 (presence of severely decayed teeth with visible pulpal involvement, ulceration caused by dislocated tooth fragments, fistula and abscess); and wearing a denture were used as predictor variables. Age, gender, marital status, education level, occupation and presence of any long standing illness were used as control variables. Multivariate zero-inflated Poisson regression analysis was performed using R-project statistical software.

    RESULTS: A total of 1277 elderly participants were included. The weighted mean(SE) OHIP-14 score of these participants was 2.95 (0.17). Having active caries (IRR=1.37, CI=1.25;1.50), PUFA>0 (IRR=1.17, CI=1.05;1.31), dental pain (IRR=1.34, CI=1.20;1.50), and wearing dentures (IRR=1.30, CI=1.17;1.44), were significantly positively associated with OHIP-14 score. Having periodontal pockets>4mm, at least one bleeding site, and anterior tooth wear were not significantly associated with the OHIP-14 score.

    CONCLUSION: Whereas previous research has suggested a moderate relationship between oral disease and quality of life in this large scale survey of older adults, the presence of active caries and the presence of one or more of the PUFA indicators are associated with impaired oral health related quality of life in older adults, but not indicators of periodontal status. The implication of this is that whilst focussing on prevention of disease, there is an ongoing need for oral health screening and treatment in this group.

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