Using mixed methods to select optimal mode of administration for a patient-reported outcome instrument for people with pressure ulcers.

BACKGROUND: When developing new measuring instruments or deciding upon one for research, consideration of the 'best' method of administration for the target population should be made. Current evidence is inconsistent in differentiating superiority of any one method in terms of quantity and quality of response. We trialed a novel mixed methods approach in early scale development to determine the best administration method for a new patient-reported outcome instrument for people with pressure ulcers (the PU-QOL). METHODS: Cognitive interviews were undertaken with 35 people with pressure ulcers to determine appropriateness of a self-completed version of the PU-QOL instrument. Quantitative analysis, including Rasch analysis, was carried out on PU-QOL data from 70 patients with pressure ulcers, randomised to self-completed or interview-administered groups, to examine data quality and differential item functioning (DIF). RESULTS: Cognitive interviews identified issues with PU-QOL self-completion. Quantitative analysis supported these findings with a large proportion of self-completed PU-QOLs returned with missing data. DIF analysis indicated administration methods did not impact the way patients from community care settings responded, supporting the equivalence of both administration versions. CONCLUSIONS: Obtaining the best possible health outcomes data requires use of appropriate methods to ensure high quality data with minimal bias. Mixed methods, with the inclusion of Rasch, provided valuable evidence to support selection of the 'best' administration method for people with PUs during early PRO instrument development. We consider our approach to be generic and widely applicable to other elderly or chronically ill populations or suitable for use in limited samples where recruitment to large field tests is often difficult.

Development and validation of a new patient-reported outcome measure for patients with pressure ulcers: the PU-QOL instrument.

BACKGROUND: Patient-reported outcome (PRO) data are integral to patient care, policy decision making and healthcare delivery. PRO assessment in pressure ulcers is in its infancy, with few studies including PROs as study outcomes. Further, there are no pressure ulcer PRO instruments available. METHODS: We used gold-standard methods to develop and evaluate a new PRO instrument for people with pressure ulcers (the PU-QOL instrument). Firstly a conceptual framework was developed forming the basis of PU-QOL scales. Next an exhaustive item pool was used to produce a draft instrument that was pretested using mixed methods (cognitive interviews and Rasch Measurement Theory). Finally, we undertook psychometric evaluation in two parts. This first part was item reduction, using PU-QOL data from 227 patients. The second part was reliability and validity evaluation of the item-reduced version using both Traditional and Rasch methods, on PU-QOL data from 229 patients. RESULTS: The final PU-QOL contains 10 scales for measuring symptoms, physical functioning, psychological well-being and social participation specific to pressure ulcers. It is intended for administration and patients rate the amount of "bother" attributed during the past week on a 3-point response scale. Scale scores are generated by summing items, with lower scores indicating better outcome. The PU-QOL instrument was found to be acceptable, reliable (Cronbach's alpha values ranging 0.89-0.97) and valid (hypothesised correlations between PU-QOL and SF-12 scores (r>0.30) and PU-QOL scales and sociodemographic variables (r<0.30) were consistent with predictions). CONCLUSIONS: The PU-QOL instrument provides a standardised method for assessing PROs, reflecting the domains in a pressure ulcer-specific conceptual framework. It is intended for evaluating patient orientated differences between interventions and in particular the impact from the perspective of patients.

Estimating preference-based single index measures for dementia using DEMQOL and DEMQOL-Proxy.

OBJECTIVE: Although condition-specific measures are commonly used in dementia, they cannot be used in analyses of cost per quality-adjusted life-year because they do not incorporate preferences. We addressed this gap by estimating two preference-based single index measures: the DEMQOL-U from the self-report DEMQOL (mild-to-moderate dementia severity) and the DEMQOL-Proxy-U from the carer-report DEMQOL-Proxy (all levels of dementia severity). METHODS: We conducted valuation studies on 593 members of the general population (306 for the DEMQOL-U, 287 for the DEMQOL-Proxy-U) using the time trade-off elicitation technique. We then fitted a range of mean and individual-level multivariate regression models to the valuation data to derive preference weights for each measure. We applied the estimated weights to a large, clinically representative sample. RESULTS: Mean observed time trade-off values ranged from 0.18 to 0.95 for DEMQOL-U and from 0.33 to 0.96 for DEMQOL-Proxy-U. The best performing models for each measure were main effects models estimated using individual-level data. DEMQOL-Proxy-U had inconsistent but insignificant coefficient estimates for one dimension. Models were estimated to remove these inconsistencies. CONCLUSION: Preference-based single index measures from DEMQOL and DEMQOL-Proxy for use in economic evaluation will enable economic evaluation using quality-adjusted life-years to be undertaken for people across the full range of dementia severity. Future research will examine how the utilities from each measure can be used and combined to populate cost-effectiveness models.

Improving the measurement of QALYs in dementia: developing patient- and carer-reported health state classification systems using Rasch analysis.

OBJECTIVES: Cost-utility analysis is increasingly used to inform resource allocation. This requires a means of valuing health states before and after intervention. Although generic measures are typically used to generate values, these do not perform well with people with dementia. We report the development of a health state classification system amenable to valuation for use in studies of dementia, derived from the DEMQOL system, measure of health-related quality of life in dementia by patient self-report (DEMQOL) and carer proxy-report (DEMQOL-Proxy). METHODS: Factor analysis was used to determine the dimensional structure of DEMQOL and DEMQOL-Proxy. Rasch analysis was subsequently used to investigate item performance across factors in terms of item-level ordering, functioning across subgroups, model fit, and severity-range coverage. This enabled the selection of one item from each factor for the classification system. A sample of people with a diagnosis of mild/moderate dementia (n = 644) and a sample of carers of those with mild/moderate dementia (n = 683) were used. RESULTS: Factor analysis found different five-factor solutions for DEMQOL and DEMQOL-Proxy. Following item reduction and selection by using Rasch analysis, a five-dimension classification for DEMQOL and a four-dimension classification for DEMQOL-Proxy were developed. Each item contained four health state levels. CONCLUSION: Combining Rasch and classical psychometric analysis is a valid method of selecting items for dementia health state classifications from both the patient and carer perspectives. The next stage is to obtain preference weights so that the measure can be used in the economic evaluation of treatment, care, and support arrangements for dementia.

The Anti-Clot Treatment Scale (ACTS) in clinical trials: cross-cultural validation in venous thromboembolism patients.

BACKGROUND: The Anti-Clot Treatment Scale (ACTS) is a 15-item patient-reported instrument of satisfaction with anticoagulant treatment. It includes a 12-item ACTS Burdens scale and a 3-item ACTS Benefits scale. Its role in clinical trials and other settings should be supported by evidence that it is both clinically meaningful and scientifically sound. The aim of the study was to evaluate the measurement performance of the ACTS (Dutch, Italian, French, German and English language versions) in patients with venous thromboembolism based on traditional psychometric methods. METHODS: ACTS Burdens and Benefits scale data from a large clinical trial (EINSTEIN DVT) involving 1336 people with venous thromboembolism were analysed at both the scale and item level. Five key psychometric properties were examined using traditional psychometric methods: acceptability, scaling assumptions, reliability (including internal consistency reliability, test-retest reproducibility); validity (including known groups and discriminant validity); and responsiveness. These methods of examination underpin the US Food and Drug Administration recommendations for patient-reported outcome instrument evaluation. RESULTS: Overall, the 12-item ACTS Burdens scale and 3-item ACTS Benefits scale met the psychometric criteria evaluated at both item and scale levels, with the exception of some relatively minor issues in the Dutch language version, which were just below reliability criteria (i.e. alpha = 0.72, test-retest intraclass correlation = 0.79). A consistent finding from item-level evaluations of aggregate endorsement frequencies and skewness suggested that response scales may be improved by reducing the number of response options from five to four. CONCLUSIONS: Both the ACTS Burdens and ACTS Benefits scales consistently satisfied traditional reliability and validity criteria across multiple language datasets, supporting it as a clinically useful patient-reported instrument of satisfaction with anticoagulant treatment in clinical trials. TRIAL REGISTRATION NUMBER: NCT00440193.

Validation of the Spanish version of the DEMQOL system.

BACKGROUND: Dementia is associated with poor quality of life, but generic measures do not fully capture main aspects of these conditions. Our aim was to validate a Spanish version of the "dementia-specific health-related quality of life" DEMQOL system. METHODS: We validated the Spanish DEMQOL and DEMQOL-Proxy in 119 people with dementia from six centers and their caregivers. Patient-reported information, including generic (WHOQOL-BREF) and dementia-specific (DEMQOL) health-related quality of life, depressive symptoms (GDS-15), functional ability (Barthel Index), subjective perception of health and demographic information, was obtained by interview. Proxy-reported information from a family caregiver about the patient's quality of life (DEMQOL-Proxy) was also obtained by interview. RESULTS: The Spanish DEMQOL showed good psychometric properties. Acceptability (14.3% missing data), internal consistency (Cronbach's alpha = 0.85) and test-retest reliability (ICC = 0.71) were good. A priori hypotheses about the relationship between DEMQOL and the WHOQOL-BREF (psychological and physical domains), GDS-15 and Barthel Index were confirmed, indicating good construct validity. Associations between DEMQOL-Proxy and other measures were weaker. A three-factor solution accounted for 44.4% of the total variance of DEMQOL, and a four-factor solution accounted for 53.3% of the total variance of DEMQOL- Proxy. CONCLUSION: The Spanish versions of DEMQOL and DEMQOL-Proxy are reliable and valid in patients with mild/moderate dementia who are living at home.

Determinants and time course of the postthrombotic syndrome after acute deep venous thrombosis.

BACKGROUND: The reason some patients with deep venous thrombosis (DVT) develop the postthrombotic syndrome is not well understood. OBJECTIVE: To determine the frequency, time course, and predictors of the postthrombotic syndrome after acute DVT. DESIGN: Prospective, multicenter cohort study. SETTING: 8 Canadian hospital centers. PATIENTS: 387 outpatients and inpatients who received an objective diagnosis of acute symptomatic DVT were recruited from 2001 to 2004. MEASUREMENTS: Standardized assessments for the postthrombotic syndrome using the Villalta scale at 1, 4, 8, 12, and 24 months after enrollment. Mean postthrombotic score and severity category at each interval was calculated. Predictors of postthrombotic score profiles over time since diagnosis of DVT were identified by using linear mixed modeling. RESULTS: At all study intervals, about 30% of patients had mild (score, 5 to 9), 10% had moderate (score, 10 to 14), and 3% had severe (score >14 or ulcer) postthrombotic syndrome. Greater postthrombotic severity category at the 1-month visit strongly predicted higher mean postthrombotic scores throughout 24 months of follow-up (1.97, 5.03, and 7.00 increase in Villalta score for mild, moderate, and severe 1-month severity categories, respectively, vs. none; P < 0.001). Additional predictors of higher scores over time were venous thrombosis of the common femoral or iliac vein (2.23 increase in score vs. distal [calf] venous thrombosis; P < 0.001), higher body mass index (0.14 increase in score per kg/m(2); P < 0.001), previous ipsilateral venous thrombosis (1.78 increase in score; P = 0.001), older age (0.30 increase in score per 10-year age increase; P = 0.011), and female sex (0.79 increase in score; P = 0.020). LIMITATIONS: Decisions to prescribe compression stockings were left to treating physicians rather than by protocol. Because international normalized ratio data were unavailable, the relationship between anticoagulation quality and Villalta scores could not be assessed. CONCLUSION: The postthrombotic syndrome occurs frequently after DVT. Patients with extensive DVT and those with more severe postthrombotic manifestations 1 month after DVT have poorer long-term outcomes.

A brief measure of perceived understanding of informed consent in a clinical trial was validated.

BACKGROUND AND OBJECTIVE: To develop and evaluate an Informed Consent Questionnaire (ICQ) for measuring self-reported perceived understanding of informed consent in a randomized clinical trial. METHODS: The study was embedded in a Department of Veterans Affairs randomized clinical trial of Gulf War veterans' illnesses (CSP#470). The trial was initiated in May 1999 at 20 hospitals and concluded in September 2001; 1,092 participants were enrolled and followed for 12 months. The reliability and validity sample included 1,086 participants evaluated at baseline, 906 at 3 months, 929 at 6 months, and 910 at 12 months. The psychometric evaluations included tests of acceptability (based on missing data, endorsement frequencies, and floor/ceiling effects), item reduction, internal consistency, and construct validity (based on Cronbach's alpha coefficients, item-total correlations, and principal components analysis). RESULTS: The ICQ had >5% missing information on some questions at baseline, indicating poor acceptability prior to the initiation of the trial; however, the scale had good acceptability at each of the follow-up visits. Psychometric evaluation following standard item reduction techniques confirmed the reliability and validity of a four-item subscale of the ICQ (ICQ-4). CONCLUSIONS: The ICQ-4 is a simple and psychometrically sound self-report measure of perceived understanding of informed consent.

VEINES-QOL/Sym questionnaire was a reliable and valid disease-specific quality of life measure for deep venous thrombosis.

OBJECTIVE: To assess the validity of VEINES-QOL/Sym, a patient-reported questionnaire to evaluate quality of life and symptoms in patients with deep venous thrombosis (DVT). STUDY DESIGN AND SETTING: Psychometric study within the Venous Thrombosis Outcomes (VETO) Study, a prospective cohort study of long-term outcomes after DVT. A total of 359 English- and French-speaking patients with acute, objectively diagnosed DVT were recruited at seven hospitals in Quebec, Canada. The VEINES-QOL/Sym questionnaire, a 26-item patient-reported measure that generates separate summary scores for symptoms (VEINES-Sym) and quality of life (VEINES-QOL) was evaluated for acceptability, reliability, validity, and responsiveness in VETO Study subjects. RESULTS: Standard psychometric tests confirmed the acceptability (missing data, item endorsement frequencies, floor and ceiling effects), reliability (internal consistency, item-total and inter-item correlations, test-retest), validity (content, construct, convergent, discriminant, known groups), and responsiveness to clinical change of the VEINES-QOL/Sym in patients with DVT. CONCLUSION: The VEINES-QOL/Sym is a practical and scientifically sound patient-reported measure of outcomes that was developed using gold-standard methods. VEINES-QOL/Sym is valid and reliable for use as a measure of quality of life and symptoms in patients with acute DVT and provides a rigorous tool to allow more comprehensive evaluation of outcomes in clinical trials and epidemiological studies of patients with DVT.

Prospective evaluation of health-related quality of life in patients with deep venous thrombosis.

BACKGROUND: To our knowledge, the burden of deep venous thrombosis from the patient's perspective has not been quantified. We evaluated health-related quality of life (QOL) after deep vein thrombosis and compared results with general population norms. METHODS: This was a multicenter prospective cohort study of 359 consecutive eligible patients with deep vein thrombosis recruited at 7 Canadian hospital centers. Quality of life was assessed at baseline and at 1 and 4 months after diagnosis using generic (36-Item Short-Form Health Survey) and disease-specific (Venous Insufficiency Epidemiological and Economic Study [VEINES]-QOL and VEINES symptom [VEINES-Sym] questionnaires) measures. Changes in QOL scores during the 4-month period were calculated, and determinants of lack of improvement in QOL were evaluated. RESULTS: During the 4 months, mean 36-Item Short-Form Health Survey physical and mental component summary scores improved by 5.1 and 4.6 points, respectively, and VEINES-QOL and VEINES-Sym scores improved by 3.1 and 2.2 points, respectively (P < .001 for time trend for all measures). However, about one third of patients had worsening of QOL during follow-up. Multivariate analyses showed that worsening of the postthrombotic syndrome score was an independent predictor of worsening of 36-Item Short-Form Health Survey physical component summary (P = .04), VEINES-QOL (P < .001), and VEINES-Sym (P < .001) scores. The 36-Item Short-Form Health Survey physical component summary scores were lower than population norms at all points assessed. CONCLUSIONS: On average, QOL improves during the 4 months following deep vein thrombosis. However, in about one third of patients, QOL deteriorates, and at 4 months, average QOL remains poorer than population norms. Worsening of the postthrombotic syndrome score is associated with worsening of QOL.

Stroke and Aphasia Quality of Life Scale-39 (SAQOL-39): evaluation of acceptability, reliability, and validity.

BACKGROUND AND PURPOSE: Health-related quality of life (HRQL) is a key outcome in stroke clinical trials. Stroke-specific HRQL scales (eg, SS-QOL, SIS) have generally been developed with samples of stroke survivors that exclude people with aphasia. We adapted the SS-QOL for use with people with aphasia to produce the Stroke and Aphasia Quality of Life Scale (SAQOL). We report results from the psychometric evaluation of the initial 53-item SAQOL and the item-reduced SAQOL-39. METHODS: We studied 95 people with long-term aphasia to evaluate the acceptability, reliability, and validity of the SAQOL and SAQOL-39 using standard psychometric methods. RESULTS: A total of 83 of 95 (87%) were able to complete the SAQOL by self-report; their results are reported here. Results supported the reliability and validity of the overall score on the 53-item SAQOL, but there was little support for hypothesized subdomains. Using factor analysis, we derived a shorter version (SAQOL-39) that identified 4 subdomains (physical, psychosocial, communication, and energy). The SAQOL-39 demonstrated good acceptability, internal consistency (Cronbach's alpha=0.74 to 0.94), test-retest reliability (intraclass correlation coefficient=0.89 to 0.98), and construct validity (corrected domain-total correlations, r=0.38 to 0.58; convergent, r=0.55 to 0.67; discriminant, r=0.02 to 0.27 validity). CONCLUSIONS: The SAQOL-39 is an acceptable, reliable, and valid measure of HRQL in people with long-term aphasia. Further testing is needed to evaluate the responsiveness of the SAQOL-39 and to investigate its usefulness in evaluative research and routine clinical practice.

The psychological impact of terrorism: an epidemiologic study of posttraumatic stress disorder and associated factors in victims of the 1995-1996 bombings in France.

OBJECTIVE: A wave of bombings struck France in 1995 and 1996, killing 12 people and injuring more than 200. The authors conducted follow-up evaluations with the victims in 1998 to determine the prevalence of and factors associated with posttraumatic stress disorder (PTSD). METHOD: Victims directly exposed to the bombings (N=228) were recruited into a retrospective, cross-sectional study. Computer-assisted telephone interviews were conducted to evaluate PTSD, per DSM-IV criteria, and to assess health status before the attack, initial injury severity and perceived threat at the time of attack, and psychological symptoms, cosmetic impairment, hearing problems, and health service use at the time of the follow-up evaluation. Factors associated with PTSD were investigated with univariate logistic regression followed by multiple logistic regression analyses. RESULTS: A total of 196 respondents (86%) participated in the study. Of these, 19% had severe initial physical injuries (hospitalization exceeding 1 week). Problems reported at the follow-up evaluation included attack-related hearing problems (51%), cosmetic impairment (33%), and PTSD (31%) (95% confidence interval=24.5%-37.5%). Results of logistic regression analyses indicated that the risk of PTSD was significantly higher among women (odds ratio=2.54), participants age 35-54 (odds ratio=2.83), and those who had severe initial injuries (odds ratio=2.79) or cosmetic impairment (odds ratio=2.74) or who perceived substantial threat during the attack (odds ratio=3.99). CONCLUSIONS: The high prevalence of PTSD 2.6 years on average after a terrorist attack emphasizes the need for improved health services to address the intermediate and long-term consequences of terrorism.

Evaluation of outcomes in community-acquired pneumonia: a guide for patients, physicians, and policy-makers.

Community-acquired pneumonia (CAP) is a key target for research and quality improvement in acute medicine. However, many of the outcome measures used in prognostic and antibiotic studies are not validated and do not capture features of outcome that are important to patients. Substitutes for traditional outcome measures include a recently validated patient-based symptom questionnaire (the CAP-Sym) and process-of-care measures. The interpretation of outcomes also depends on the quality of the study design and methods used. This paper discusses the advantages and disadvantages of outcome, process-of-care, and economic measures in CAP and the interpretation of these measures in randomised and observational studies. A core set of measures for use in clinical CAP research and performance measurement is proposed.

The community-acquired pneumonia symptom questionnaire: a new, patient-based outcome measure to evaluate symptoms in patients with community-acquired pneumonia.

STUDY OBJECTIVE: s: To develop and validate a patient-based outcome measure to evaluate symptoms in patients with community-acquired pneumonia (CAP). DESIGN: A psychometric study within an international, prospective, randomized, double-blind study. The CAP-symptom questionnaire (CAP-Sym) is a new, 18-item, patient-reported outcome measure that evaluates the bothersomeness of CAP-related symptoms during the past 24 h using a 6-point Likert scale. We used "gold standard" psychometric methods to comprehensively evaluate the acceptability, reliability, validity, and responsiveness of the CAP-Sym. SETTING: Sixty-four centers in 13 countries (France, Germany, Hungary, Israel, Italy, Norway, Poland, Portugal, South Africa, Spain, Sweden, Switzerland, United Kingdom). PATIENTS: Five hundred fifty-six patients with CAP, recruited from outpatient clinics, general practice, and hospital centers. INTERVENTIONS: Randomization 1:1 to moxifloxacin (400 mg once daily), oral or standard oral treatment (amoxicillin, 1 g tid, or clarithromycin, 500 mg bid), alone or in combination, for up to 14 days. RESULTS: Standard psychometric tests confirmed the acceptability (item nonresponse, item-endorsement frequencies, item/scale floor and ceiling effects), reliability (internal consistency, item-total and inter-item correlations, test-retest reliability), validity (content, construct, convergent, discriminant, known groups), and responsiveness of the CAP-Sym. CONCLUSIONS: The CAP-Sym is a practical and scientifically sound patient-based outcome measure of CAP-related symptoms that has been developed using "gold standard" methods. As the only fully validated measure of symptoms in patients with CAP, which is quick and easy to administer and is more responsive than the generic Medical Outcomes Study 36-Item Short-Form Health Survey, the CAP-Sym provides a practical and rigorous method for improving the evaluation of outcomes in clinical trials and audit.

Clinical outcomes and quality of life in elderly patients on peritoneal dialysis versus hemodialysis.

OBJECTIVE: To compare clinical outcomes and quality of life (QOL) in elderly patients on peritoneal dialysis (PD) and hemodialysis (HD) in the North Thames Dialysis Study. DESIGN: A 12-month prospective cohort study. SETTING: Four hospital-based renal units in London, UK. PATIENTS: 174 patients that were 70 years or older at the start of dialysis, separated into two cohorts: 78 new patients (36 PD, 42 HD) that were recruited after 90 days of chronic dialysis; and 96 stock patients (42 PD, 54 HD) that were already on dialysis during the recruitment period. MAIN OUTCOME MEASURES: 12-month survival and hospitalization rate, and QOL assessed at baseline and at 6 and 12 months by the SF-36 and the Symptoms/Problems scale of the Kidney Disease Quality of Life Questionnaire (KDQOL). RESULTS: Peritoneal dialysis and HD patients were similar for sociodemographic and clinical characteristics. Annual mortality and hospitalization rates in PD versus HD patients were 26.1 versus 26.4 deaths/100 person-years and 1.9 versus 2.0 admissions/person-year, respectively. Adjusted relative risks showed no effect of modality on clinical outcomes. Multiple linear regression analyses of QOL at baseline showed similar SF-36 scores between PD and HD patients, but higher KDQOL scores in PD patients (3.5 points higher, 95% confidence interval 0.3-6.6). There was, however, no effect of dialysis modality on QOL at 6 or 12 months. CONCLUSIONS: Clinical outcomes and QOL are similar in elderly people on PD and HD. Peritoneal dialysis is a viable option for more than a carefully selected minority of elderly people requiring dialysis.

Patient-reported outcome measures for chronic wounds with particular reference to pressure ulcer research: a systematic review.

OBJECTIVES: Pressure ulcers are a major health problem, affect patient psychological, physical and social functioning, and cause significant treatment burden. For comprehensive assessment of the benefits of an intervention, patient-reported evidence of the impact of an intervention on important patient outcomes should be made. We systematically reviewed the quality of life literature on chronic wounds to determine the suitability of generic and chronic wound-specific outcome measures for use in evaluating patient outcomes in pressure ulcer research. DESIGN: A systematic review of the literature. DATA SOURCES: Searches of eight electronic databases from inception until May 2012 were undertaken. REVIEW METHODS: Quality of life domains, item content and content relevance were determined for identified outcome measures. The content validity of identified measures was assessed against an empirically derived pressure ulcer-specific conceptual framework. RESULTS: Three generic and 14 chronic wound measures were identified but no pressure ulcer-specific measures. None of the existing measures cover all quality of life domains important in pressure ulcers. One condition-specific measure, the Venous Leg Ulcer Measure, matched most closely conceptually, but failed to represent three important domains and contained items not specific to pressure ulcers. CONCLUSIONS: Currently, outcomes important in pressure ulcers are inadequately covered by generic and chronic wound-specific instruments despite similar conceptual models. Highlighted is the need for clear conceptualisation of content as well as determining appropriateness when selecting outcome measures in the future.

When to use broader internalising and externalising subscales instead of the hypothesised five subscales on the Strengths and Difficulties Questionnaire (SDQ): data from British parents, teachers and children.

The Strengths and Difficulties Questionnaire (SDQ) is a widely used child mental health questionnaire with five hypothesised subscales. There is theoretical and preliminary empirical support for combining the SDQ's hypothesised emotional and peer subscales into an 'internalizing' subscale and the hypothesised behavioral and hyperactivity subscales into an 'externalizing' subscale (alongside the fifth prosocial subscale). We examine this using parent, teacher and youth SDQ data from a representative sample of 5-16 year olds in Britain (N = 18,222). Factor analyses generally supported second-order internalizing and externalizing factors, and the internalizing and externalizing subscales showed good convergent and discriminant validity across informants and with respect to clinical disorder. By contrast, discriminant validity was poorer between the emotional and peer subscales and between the behavioral, hyperactivity and prosocial subscales. This applied particularly to children with low scores on those subscales. We conclude that there are advantages to using the broader internalizing and externalizing SDQ subscales for analyses in low-risk samples, while retaining all five subscales when screening for disorder.

Development of a conceptual framework of health-related quality of life in pressure ulcers: a patient-focused approach.

BACKGROUND: Evaluating outcomes such as health-related quality of life is particularly important and relevant in skin conditions such as pressure ulcers where the condition and associated interventions pose substantial burden to patients. Measures to evaluate such outcomes need to be developed by utilising patient-perspective to ensure that content and conceptualisation is relevant to patients. OBJECTIVES: Our aim was to develop a conceptual framework of health-related quality of life in pressure ulcers, based on patients' views about the impact of pressure ulcers and interventions on health-related quality of life to inform the development of a new patient-reported outcome measure. SETTING, PARTICIPANTS AND METHODS: We developed a working conceptual framework based on a previous review of the literature, then used semi-structured qualitative interviews with 30 adults with pressure ulcers (22-94 years) purposively sampled from hospital, community and rehabilitation care settings in England and Northern Ireland to obtain patients' views, and thematic content analysis and review by a multidisciplinary expert group to develop the final conceptual framework. FINDINGS: Our conceptual model includes four health-related quality of life domains (symptoms, physical functioning, psychological well-being, social functioning), divided into 13 sub-domains and defined by specific descriptive components. CONCLUSIONS: We have identified health-related quality of life outcomes that are important to people with pressure ulcers and developed a conceptual framework using robust and systematic methods, which provides the basis for the development of a new pressure ulcer-specific measure of health-related quality of life.

Mathematical coupling may account for the association between baseline severity and minimally important difference values.

OBJECTIVE: To generate anchor-based values for the "minimally important difference" (MID) for a number of commonly used patient-reported outcome (PRO) measures and to examine whether these values could be applied across the continuum of preoperative patient severity. STUDY DESIGN AND SETTING: Six prospective cohort studies of patients undergoing elective surgery at hospitals in England and Wales. Patients completed questionnaires about their health and health-related quality of life before and after surgery. MID values were calculated using the mean change score for a reference group of patients who reported they were "a little better" after surgery minus the mean change score for those who said they were "about the same." Pearson's correlation was used to examine the association between baseline severity and change scores in the reference group. Baseline severity was expressed in two ways: first in terms of preoperative scores and second in terms of the average of pre- and postoperative scores (Oldham's method). RESULTS: Of the 10 PRO measures examined, eight demonstrated a moderate or high positive association between preoperative scores and MID values. Only two measures demonstrated such an association when Oldham's measure of baseline severity was used. CONCLUSION: In general, there is little association between baseline severity and MID values. However, a moderate association persists for some measures, and it is recommended that researchers continue to test for this relationship when generating anchor-based MID values from change scores.