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ABSTRACT: Objective: To determine the content, structural, and construct validity of the Dutch version of the Neck Disability Index (NDI). Study Design and Setting: To assess content validity, 11 neck pain experts and 10 patients commented on the construct, comprehen-siveness, and relevance of the NDI. Structural validity was assessed by item factor analysis (FA) and item response theory modeling using the generalized partial credit model. Differential item functioning (DIF) analysis for gender was examined. Pearson correlation coefficient with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was calculated to assess construct validity. Results: In addition to a suboptimal translation, we found a lack of consensus on the construct the NDI intends to measure. Experts and patients suggested that the NDI measures more than physical functioning. Unidimensionality of the NDI could not be confirmed. DIF anal-ysis for gender showed DIF for the headache item. The goodness-of-fit statistics for FA with one factor were satisfactory when the item ''concentration'' was omitted. A correlation of 0.75 with the DASH was found supporting construct validity. Conclusion: It is questionable whether in research the NDI should be the instrument of choice for use as a primary outcome measure. Definition of the construct to be measured is a prerequisite for the assessment of validity.
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ABSTRACT: OBJECTIVE: To determine the content, structural, and construct validity of the Dutch version of the Neck Disability Index (NDI). STUDY DESIGN AND SETTING: To assess content validity, 11 neck pain experts and 10 patients commented on the construct, comprehensiveness, and relevance of the NDI. Structural validity was assessed by item factor analysis (FA) and item response theory modeling using the generalized partial credit model. Differential item functioning (DIF) analysis for gender was examined. Pearson correlation coefficient with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was calculated to assess construct validity. RESULTS: In addition to a suboptimal translation, we found a lack of consensus on the construct the NDI intends to measure. Experts and patients suggested that the NDI measures more than physical functioning. Unidimensionality of the NDI could not be confirmed. DIF analysis for gender showed DIF for the headache item. The goodness-of-fit statistics for FA with one factor were satisfactory when the item "concentration" was omitted. A correlation of 0.75 with the DASH was found supporting construct validity. CONCLUSION: It is questionable whether in research the NDI should be the instrument of choice for use as a primary outcome measure. Definition of the construct to be measured is a prerequisite for the assessment of validity.
Journal of clinical epidemiology 04/2013; · 2.96 Impact Factor
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ABSTRACT: Clinicians are interested in observer variation in terms of the probability of other raters (interobserver) or themselves (intraobserver) obtaining the same answer. Cohen's κ is commonly used in the medical literature to express such agreement in categorical outcomes. The value of Cohen's κ, however, is not sufficiently informative because it is a relative measure, while the clinician's question of observer variation calls for an absolute measure. Using an example in which the observed agreement and κ lead to different conclusions, we illustrate that percentage agreement is an absolute measure (a measure of agreement) and that κ is a relative measure (a measure of reliability). For the data to be useful for clinicians, measures of agreement should be used. The proportion of specific agreement, expressing the agreement separately for the positive and the negative ratings, is the most appropriate measure for conveying the relevant information in a 2×2 table and is most informative for clinicians.
BMJ (Clinical research ed.). 01/2013; 346:f2125.
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ABSTRACT: OBJECTIVES: To compare available instruments and investigate which best measure the quality of end-of-life care (QOC) and quality of dying (QOD) in long term care settings, in terms of validity, reliability, and feasibility. DESIGN: Family and professional caregivers of long term care decedents completed postdeath interviews and questionnaires between November 2007 and April 2009. SETTING: Nursing home and residential care/assisted living settings in the United States and the Netherlands. PARTICIPANTS: Two hundred and sixty four families of decedents with (48%) and without (52%) dementia in the United States, and 70 families and 103 professional caregivers of decedents with dementia in the Netherlands. MEASUREMENTS: Ten instruments to evaluate the QOC and QOD in long term care, an additional overall assessment of QOC/QOD, and an assessment of the perception of the relevance and ease of use of each instrument. Criteria for validity, reliability, and feasibility were set forth for good, intermediate, and poor performance. RESULTS: None of the instruments scored positively on all criteria. In both countries, of the QOC instruments, the End-of-Life in Dementia-Satisfaction With Care (EOLD-SWC) best met the criteria, followed by the Family Assessment of Treatment at the End-of-Life Short Version, the Family Perception of Care Scale, and Family Perception of Physician-Family Caregiver Communication. Of the QOD instruments, the End-of-Life in Dementia-Comfort Assessment at Dying (EOLD-CAD) and Mini-Suffering State Examination (MSSE) met more of the criteria than others. The EOLD-CAD performed better on content and construct validity than the MSSE. The MSSE performed better on feasibility. CONCLUSION: We recommend the EOLD-SWC to measure QOC, and the EOLD-CAD and MSSE to measure QOD in populations with dementia and in mixed long term care populations of nursing home or residential care home/assisted living residents, because they performed best in both countries. Use of the same instruments allows for comparison of the results between studies.
Journal of the American Medical Directors Association 11/2012; · 4.64 Impact Factor
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ABSTRACT: CONTEXT: More people are surviving into old age, and chronic diseases tend to become more common with age. Ill health and disability can lead to concerns about loss of personal dignity. OBJECTIVES: To investigate whether health status affects the perceptions of factors influencing personal dignity at the end of life, and the relationship between those perceptions and sociodemographic characteristics. METHODS: A subsample (n=2282) of a large advance directives cohort study was used. Three different health status groups (good, moderate, and poor) were defined based on the Euroqol-5D and a question on whether they had an illness. For each health status group, we calculated the percentage of respondents who indicated the extent to which the items of the Patient Dignity Inventory would influence their dignity as (very) large. Logistic regression analyses were used to investigate the associations between the perceptions of factors influencing personal dignity and sociodemographics. RESULTS: The percentage of respondents who indicated the factors as having a (very) large influence on dignity at the end of life were not significantly different for the three health status groups, except for three physical items on symptoms, roles, and routines. Those items were significantly more influential on dignity for people with a poor health status. Gender, old age, having a partner, and having a belief or religion that is important to one's life were associated with an understanding of factors influential to dignity. CONCLUSION: Health status seems only to affect the perceptions of physical factors maintaining dignity at the end of life. This might suggest that the understanding of dignity will not substantially change as health status changes and may support starting advance care planning early.
Journal of pain and symptom management 11/2012; · 2.42 Impact Factor
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ABSTRACT: When designing prediction models by complete case analysis (CCA), missing information in either baseline (predictors) or outcomes may lead to biased results. Multiple imputation (MI) has been shown to be suitable for obtaining unbiased results. This study provides researchers with an empirical illustration of the use of MI in a data set on low back pain, by comparing MI with the more commonly used CCA. Effects will be shown of imputing missing information on the composition and performance of prognostic models, distinguishing imputation of missing values in baseline characteristics and outcome data.
Data came from the Beliefs about Backpain cohort, a study of psychologic obstacles to recovery in primary care back pain patients in the United Kingdom. Candidate predictors included demographics, back pain characteristics, and psychologic variables. Complete case analysis was compared with MI within patients with complete outcome but missing baseline data (n = 809) and patients with missing baseline or outcome data (n = 1591). Multiple imputation was performed by a Multiple Imputation by Chained Equations procedure.
Cases with missing outcome data (n = 782, 49.1%) or with missing baseline data (n = 116, 8%) both differed from complete cases regarding the distribution of some predictors and more often had a poor outcome. When comparing CCA with MI, model composition showed to be affected.
Complete case analysis can give biased results, even when only small amounts of data are missing. Now that MI is available in standard statistical software, we recommend that it be used to handle missing data.
Journal of manipulative and physiological therapeutics 07/2012; 35(6):464-71. · 1.06 Impact Factor
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ABSTRACT: The objectives of this systematic review are to examine how researchers report missing data in questionnaires and to provide an overview of current methods for dealing with missing data.
We included 262 studies published in 2010 in 3 leading epidemiologic journals. Information was extracted on how missing data were reported, types of missing, and methods for dealing with missing data.
Seventy-eight percent of the studies lacked clear information about the measurement instruments. Missing data in multi-item instruments were not handled differently from other missing data. Complete-case analysis was most frequently reported (81% of the studies), and the selectivity of missing data was seldom examined.
Although there are specific methods for handling missing data in item scores and in total scores of multi-item instruments, these are seldom applied. Researchers mainly use complete-case analysis for both types of missing, which may seriously bias the study results.
Epidemiology (Cambridge, Mass.) 05/2012; 23(5):729-32. · 5.51 Impact Factor
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ABSTRACT: The purpose of this study was to qualitatively evaluate patients understanding and interpretation of the wording used in test
items of the Tampa Scale of Kinesiophobia (TSK). The TSK was developed to measure fear of movement in patients suffering from
low back pain. The TSK is being increasingly used for other pain conditions. Patients with sub-acute neck pain experience
problems while completing this questionnaire. The aim of this study was to elicit these problems. The study was conducted
within the framework of a randomised controlled trial. The Three-Step Test Interview (TSTI) was used to collect data on the
thoughts or considerations of respondents while completing the TSK. In the analysis, each transcribed interview was divided
into three segments. The thoughts and considerations were then analysed and categorised per item. During the TSTI two problems
were identified. One concerned the meaning of specific words used, like “dangerous” and “injury”. The other problem was that
several implicit assumptions within some items make it difficult for respondents to answer these items. It was concluded that
in the development and validation of questionnaires like the TSK, not only quantitative psychometric properties are important,
but also qualitative research has an important contribution to enhance applicability.
Quality and Quantity 04/2012; 43(5):773-780. · 0.77 Impact Factor
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The spine journal: official journal of the North American Spine Society 02/2012; 12(2):177. · 2.90 Impact Factor
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ABSTRACT: Identifying relevant subgroups in patients with low back pain (LBP) is considered important to guide physical therapy practice and to improve outcomes. The aim of the present study was to assess the cost-effectiveness of a modified version of Delitto's classification-based treatment approach compared with usual physical therapy care in patients with sub-acute and chronic LBP with 1 year follow-up.
All patients were classified using the modified version of Delitto's classification-based system and then randomly assigned to receive either classification-based treatment or usual physical therapy care. The main clinical outcomes measured were; global perceived effect, intensity of pain, functional disability and quality of life. Costs were measured from a societal perspective. Multiple imputations were used for missing data. Uncertainty surrounding cost differences and incremental cost-effectiveness ratios was estimated using bootstrapping. Cost-effectiveness planes and cost-effectiveness acceptability curves were estimated.
In total, 156 patients were included. The outcome analyses showed a significantly better outcome on global perceived effect favoring the classification-based approach, and no differences between the groups on pain, disability and quality-adjusted life-years. Mean total societal costs for the classification-based group were 2,287, and for the usual physical therapy care group 2,020. The difference was 266 (95% CI -720 to 1,612) and not statistically significant. Cost-effectiveness analyses showed that the classification-based approach was not cost-effective in comparison with usual physical therapy care for any clinical outcome measure.
The classification-based treatment approach as used in this study was not cost-effective in comparison with usual physical therapy care in a population of patients with sub-acute and chronic LBP.
European Spine Journal 01/2012; 21(7):1290-300. · 1.97 Impact Factor
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ABSTRACT: There is no valid, fast and easy-to-apply set of criteria to determine (risk of) undernutrition in community-dwelling older persons. The aim of this study was to develop and validate such criteria.
Selection of potential anthropometric and undernutrition-related items was based on consensus literature. The criteria were developed using 15-year mortality in community-dwelling older persons ≥ 65 years (Longitudinal Aging Study Amsterdam, n = 1687) and validated in an independent sample (InCHIANTI, n = 1142).
Groups distinguished were: (1) undernutrition (mid-upper arm circumference <25 cm or involuntary weight loss ≥4 kg/6 months); (2) risk of undernutrition (poor appetite and difficulties climbing staircase); and (3) no undernutrition (others). Respective hazard ratio's for 15-year mortality were: (1) 2.22 (95% CI 1.83-2.69); and (2) 1.57 (1.22-2.01) ((3) = reference). The area under the curve (AUC) was 0.55. Comparable results were found stratified by sex, excluding cancer/obstructive lung disease/(past) smoking, using 6-year mortality, and applying results to the InCHIANTI study (hazard ratio's 2.12 and 2.46, AUC 0.59).
The developed set of criteria (SNAQ⁶⁵⁺) for determining (risk of) undernutrition in community-dwelling older persons shows good face validity and moderate predictive validity based on the consistent association with mortality in a second independent study sample.
Clinical nutrition (Edinburgh, Scotland) 11/2011; 31(3):351-8. · 3.27 Impact Factor
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ABSTRACT: In 1980 the Waddell score, consisting of 8 non-organic or behavioural signs, was developed to measure illness behaviour in patients with low back pain. There is some debate about whether the Waddell score is a valid screening instrument for illness behaviour and psychological distress, or whether it merely reflects elevated pain levels and diminished functional physical capacities.
The purpose of this study was to examine the construct validity of the Waddell score.
In this cross-sectional study, a total of 20 hypotheses about the associations between the Waddell score and measures from different domains were formulated a priori, based on a Medline database search (1980-2010). These hypotheses were tested in a sample of 229 patients with chronic low back pain who attended an outpatient rehabilitation centre.
The percentage of hypotheses that were confirmed for the association between the Waddell score and the domain pain was 100%, for the domain physical 80%, for the domain illness behaviour 80% and 50% for the domain psychological. Correlation coefficients and kappa values varied between 0.06 and 0.44 for the measures that were expected to be associated with the Waddell score.
Most of our challenging a priori hypotheses were accepted, and the Waddell score was found to have satisfactory cross-sectional construct validity. However, the presence of Waddell signs does not indicate exactly what the specific problems are and must therefore be conceptualized and understood in the total clinical picture of the patient. The association between the Waddell score and measures from different domains is weak. The Waddell score cannot be regarded as a straightforward psychological "screener".
The Clinical journal of pain 09/2011; 28(4):309-17. · 3.01 Impact Factor
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ABSTRACT: Prospective cohort study.
We explored long-term associations between physical load exposure and chronic low back pain (LBP) using data from an ongoing population-based cohort study.
Physical load in work or daily life is often studied in relation to LBP. Most studies are cross-sectional or have a limited follow-up.
Between 1993 and 2007, 4738 men and women aged 25 to 64 years were measured maximal 3 times with 5-year intervals. Physical load in daily activities (9 items, e.g., awkward postures, mechanical vibration) was assessed by questionnaire at 2 measurements and chronic LBP 3 times. Physical load exposure at both measurements was described. Multivariable logistic regression analyses were adjusted for sex, age, education, work status, body mass index, physical activity, and smoking.
Despite stable prevalence rates of physical load exposure, about 50% of the participants exposed changed their exposure during a 5-year period. 7.2% of the participants reported awkward postures at 2 measurements, 8.4% at the first measurement only, and 6.8% at the second measurement only. Among all physical load variables, associations with chronic LBP were found only for awkward postures. An increased risk for incident chronic LBP was found in participants exposed twice to awkward postures. In contrast, only single exposure to awkward postures was associated with persistence of chronic LBP.
Awkward postures were associated with chronic LBP in the general population. Exposure to awkward postures at 2 measurements with 5 years in between did increase the risk for incident chronic LBP, but not for persistence of chronic LBP.
Spine 09/2011; 37(9):788-96. · 2.08 Impact Factor
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ABSTRACT: Quality of care for long-term care (LTC) residents with dementia at the end-of-life is often evaluated using standardized instruments that were not developed for or thoroughly tested in this population. Given the importance of using appropriate instruments to evaluate the quality of care (QOC) and quality of dying (QOD) in LTC, we compared the validity and reliability of ten available instruments commonly used for these purposes.
We performed prospective observations and retrospective interviews and surveys of family (n = 70) and professionals (n = 103) of LTC decedents with dementia in the Netherlands.
Instruments within the constructs QOC and QOD were highly correlated, and showed moderate to high correlation with overall assessments of QOC and QOD. Prospective and retrospective ratings using the same instruments differed little. Concordance between family and professional scores was low. Cronbach's alpha was mostly adequate. The EOLD-CAD showed good fit with pre-assumed factor structures. The EOLD-SWC and FPCS appear most valid and reliable for measuring QOC, and the EOLD-CAD and MSSE for measuring QOD. The POS performed worst in this population.
Our comparative study of psychometric properties of instruments allows for informed selection of QOC and QOD measures for LTC residents with dementia.
Quality of Life Research 08/2011; 21(4):671-84. · 2.30 Impact Factor
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ABSTRACT: The COSMIN checklist is a standardized tool for assessing the methodological quality of studies on measurement properties. It contains 9 boxes, each dealing with one measurement property, with 5-18 items per box about design aspects and statistical methods. Our aim was to develop a scoring system for the COSMIN checklist to calculate quality scores per measurement property when using the checklist in systematic reviews of measurement properties.
The scoring system was developed based on discussions among experts and testing of the scoring system on 46 articles from a systematic review. Four response options were defined for each COSMIN item (excellent, good, fair, and poor). A quality score per measurement property is obtained by taking the lowest rating of any item in a box ("worst score counts").
Specific criteria for excellent, good, fair, and poor quality for each COSMIN item are described. In defining the criteria, the "worst score counts" algorithm was taken into consideration. This means that only fatal flaws were defined as poor quality. The scores of the 46 articles show how the scoring system can be used to provide an overview of the methodological quality of studies included in a systematic review of measurement properties.
Based on experience in testing this scoring system on 46 articles, the COSMIN checklist with the proposed scoring system seems to be a useful tool for assessing the methodological quality of studies included in systematic reviews of measurement properties.
Quality of Life Research 07/2011; 21(4):651-7. · 2.30 Impact Factor
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ABSTRACT: To identify signs and symptoms that should alert clinicians to the need for additional psychological assessment in patients with chronic low back pain (CLBP).
In this prospective cohort study, 229 consecutive patients with CLBP who attended an outpatient rehabilitation center were assessed by psychologists and physical therapists before their treatment started. The signs and symptoms assessed by the physical therapists were compared with the assessments made by the psychologists, which were considered to be the reference standard (relevant psychological disturbances, yes or no). Univariable and multivariable regression methods were applied to investigate which signs and symptoms were associated with the reference standard. A receiver operator characteristic (ROC) curve was constructed to assess the overall accuracy of the final model.
The psychologists classified 53% of the patients as having relevant psychological disturbances. Univariable analysis revealed statistically significant differences (P<0.05) between the 2 patient groups (relevant psychological disturbances, yes or no) for 10 of the 17 signs and symptoms. Multivariate analysis yielded a screening instrument consisting of the following 4 signs and symptoms: presence of Waddell signs, elevated scores on the pain drawing, absence of a directional preference, and daily use of analgesic medication for CLBP [area under the ROC curve, 0.81 (95% confidence interval: 0.75, 0.87)].
This study established a clinically useful screening instrument for the identification of patients with CLBP who might benefit from additional psychological assessment in an outpatient rehabilitation setting. Further research is needed to confirm our preliminary results.
The Clinical journal of pain 06/2011; 28(1):23-31. · 3.01 Impact Factor
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ABSTRACT: Training in and assessment of consultation skills are high on the agenda of vocational training institutes for postgraduate training. There is a need to establish valid and reliable instruments to assess consultation skills in authentic settings. We investigated the number of assessors and observations needed to achieve reliable assessments of the consultation skills of general practice trainees (GPTs) using a communication instrument (MAAS-Global) and either standardised patient (SP) encounters or videotaped real patient (RP) encounters.
Eight teachers at the Vrije Universiteit (VU) University Medical Centre in Amsterdam attended a training course on the use of the MAAS-Global instrument, which they subsequently used to assess the consultation skills of 53 GPTs in 176 videotaped consultations (102 with SPs, 74 with RPs). All consultations were randomly allocated and assessed by two teachers independently. The reliability of the ratings was estimated using generalisability theory.
It was easier to obtain acceptable reliability using RP consultations than SP consultations. Two assessors and five consultations were required to achieve minimal reliability (generalisability coefficient 0.7) with RPs, whereas three assessors and 30 consultations were needed to achieve minimal reliability with SPs.
Inter-observer and context variability in the assessment of the consultation skills of GPTs remains high. To achieve acceptable levels of reliability, large samples of observations are required in both formats, but, interestingly, RP encounters require a smaller sample than SP encounters.
Medical Education 06/2011; 45(6):578-84. · 3.18 Impact Factor
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ABSTRACT: Long-term care (LTC) settings have become a significant site for end-of-life care; consequently, instruments that assess the quality of dying and care may be useful in these settings.
To evaluate the content of available measurement instruments to assess the quality of dying and care when dying.
Qualitative content analysis to categorize items as structure of care, process of care, satisfaction with health care (the first three representing quality of care and its evaluation), quality of dying, or patient factors.
Instruments that measure mostly quality of care and its evaluation are the Family Perception of Physician-Family Caregiver Communication, End-of-Life in Dementia (EOLD) Satisfaction With Care, Family Perception of Care Scale, Toolkit of Instruments to Measure End-of-Life Care after-death bereaved family member interview (nursing home version), and the Family Assessment of Treatment at the End-of-Life Short version. Instruments measuring quality of dying are the EOLD-Comfort Assessment in Dying, EOLD-Symptom Management, Mini-Suffering State Examination, and Palliative Care Outcome Scale. The Quality of Dying in Long-Term Care measures care and dying. The Minimum Data Set-Palliative Care measures mostly dying and patient factors. The instruments differ in dementia specificity, time of administration, and respondent.
Instruments that assess quality when dying differ in several ways and most do not measure a single construct, which is relevant to guiding and evaluating care. Comparing psychometric properties and usefulness of instruments that measure similar constructs is the next step in determining which are best suited for use in LTC.
Journal of pain and symptom management 05/2011; 42(6):852-63. · 2.42 Impact Factor
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ABSTRACT: The aim of this study was to obtain an overview of the methodological quality of studies on the measurement properties of neck pain and disability questionnaires and to describe how well various aspects of the design and statistical analyses of studies on measurement properties are performed.
A systematic review was performed of published studies on the measurement properties of neck pain and disability questionnaires. Two reviewers independently rated the quality of the studies using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist. This checklist was developed in an international Delphi consensus study.
A total of 47 articles were included on the measurement properties of 8 different questionnaires. The methodological quality of the included studies was adequate on some aspects (often, adequate statistical analyses are used for assessing reliability, measurement error, and construct validity) but can be improved on other aspects. The most important methodological aspects that need to be improved are as follows: assessing unidimensionality in internal consistency analysis, stable patients and similar test conditions in studies on reliability and measurement error, and more emphasis on the relevance and comprehensiveness of the items in content validity studies. Furthermore, it is recommended that studies on construct validity and responsiveness should be based on predefined hypotheses and that better statistical methods should be used in responsiveness studies.
Considering the importance of adequate measurement properties, it is concluded that, in the field of measuring neck pain and disability, there is room for improvement in the methodological quality of studies measurement properties.
Journal of manipulative and physiological therapeutics 05/2011; 34(4):261-72. · 1.06 Impact Factor
