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author:("agell, Peter")
1.  Factors associated with fear of falling in people with Parkinson’s disease 
BMC Neurology  2014;14:19.
This study aimed to comprehensibly investigate potential contributing factors to fear of falling (FOF) among people with idiopathic Parkinson’s disease (PD).
The study included 104 people with PD. Mean (SD) age and PD-duration were 68 (9.4) and 5 (4.2) years, respectively, and the participants’ PD-symptoms were relatively mild. FOF (the dependent variable) was investigated with the Swedish version of the Falls Efficacy Scale, i.e. FES(S). The first multiple linear regression model replicated a previous study and independent variables targeted: walking difficulties in daily life; freezing of gait; dyskinesia; fatigue; need of help in daily activities; age; PD-duration; history of falls/near falls and pain. Model II included also the following clinically assessed variables: motor symptoms, cognitive functions, gait speed, dual-task difficulties and functional balance performance as well as reactive postural responses.
Both regression models showed that the strongest contributing factor to FOF was walking difficulties, i.e. explaining 60% and 64% of the variance in FOF-scores, respectively. Other significant independent variables in both models were needing help from others in daily activities and fatigue. Functional balance was the only clinical variable contributing additional significant information to model I, increasing the explained variance from 66% to 73%.
The results imply that one should primarily target walking difficulties in daily life in order to reduce FOF in people mildly affected by PD. This finding applies even when considering a broad variety of aspects not previously considered in PD-studies targeting FOF. Functional balance performance, dependence in daily activities, and fatigue were also independently associated with FOF, but to a lesser extent. Longitudinal studies are warranted to gain an increased understanding of predictors of FOF in PD and who is at risk of developing a FOF.
PMCID: PMC3904169  PMID: 24456482
Fear of falling; Physical therapy; Parkinson’s disease; Postural Balance; Rehabilitation
2.  Diagnostic performance of the Minimal Eating Observation and Nutrition Form - Version II (MEONF-II) and Nutritional Risk Screening 2002 (NRS 2002) among hospital inpatients - a cross-sectional study 
BMC Nursing  2011;10:24.
The usefulness of the nutritional screening tool Minimal Eating Observation and Nutrition Form - Version II (MEONF-II) relative to Nutritional Risk Screening 2002 (NRS 2002) remains untested. Here we attempted to fill this gap by testing the diagnostic performance and user-friendliness of the MEONF-II and the NRS 2002 in relation to the Mini Nutritional Assessment (MNA) among hospital inpatients.
Eighty seven hospital inpatients were assessed for nutritional status with the 18-item MNA (considered as the gold standard), and screened with the NRS 2002 and the MEONF-II.
The MEONF-II sensitivity (0.61), specificity (0.79), and accuracy (0.68) were acceptable. The corresponding figures for NRS 2002 were 0.37, 0.82 and 0.55, respectively. MEONF-II and NRS 2002 took five minutes each to complete. Assessors considered MEONF-II instructions and items to be easy to understand and complete (96-99%), and the items to be relevant (87%). For NRS 2002, the corresponding figures were 75-93% and 79%, respectively.
The MEONF-II is an easy to use, relatively quick and sensitive screening tool to assess risk of undernutrition among hospital inpatients. With respect to user-friendliness and sensitivity the MEONF-II seems to perform better than the NRS 2002, although larger studies are needed for firm conclusions. The different scoring systems for undernutrition appear to identify overlapping but not identical patient groups. A potential limitation with the study is that the MNA was used as gold standard among patients younger than 65 years.
PMCID: PMC3305676  PMID: 22185436
3.  Walking Ability Is a Major Contributor to Fear of Falling in People with Parkinson's Disease: Implications for Rehabilitation 
Parkinson's Disease  2011;2012:713236.
Although fear of falling (FOF) is common in people with Parkinson's disease (PD), there is a lack of research investigating potential predictors of FOF. This study explored the impact of motor, nonmotor, and demographic factors as well as complications of drug therapy on FOF among people with PD. Postal survey data (including the Falls Efficacy Scale, FES) from 154 nondemented people with PD were analyzed using multiple regression analyses. Five significant independent variables were identified explaining 74% of the variance in FES scores. The strongest contributing factor to FOF was walking difficulties (explaining 68%), followed by fatigue, turning hesitations, need for help in daily activities, and motor fluctuations. Exploring specific aspects of walking identified three significant variables explaining 59% of FOF: balance problems, limited ability to climb stairs, and turning hesitations. These results have implications for rehabilitation clinicians and suggest that walking ability is the primary target in order to reduce FOF. Specifically, balance, climbing stairs, and turning seem to be of particular importance.
PMCID: PMC3175698  PMID: 21941686
4.  Cut-off scores for the Minimal Eating Observation and Nutrition Form – Version II (MEONF-II) among hospital inpatients 
Food & Nutrition Research  2011;55:10.3402/fnr.v55i0.7289.
Background and objective
The newly developed Minimal Eating Observation and Nutrition Form – Version II (MEONF-II) has shown promising sensitivity and specificity in relation to the Mini Nutritional Assessment (MNA). However, the suggested MEONF-II cut-off scores for deciding low/moderate and high risk for undernutrition (UN) (>2 and >4, respectively) have not been decided based on statistical criteria but on clinical reasoning. The objective of this study was to identify the optimal cut-off scores for the MEONF-II in relation to the well-established MNA based on statistical criteria.
Cross-sectional study.
The study included 187 patients (mean age, 77.5 years) assessed for nutritional status with the MNA (full version), and screened with the MEONF-II. The MEONF-II includes assessments of involuntary weight loss, Body Mass Index (BMI) (or calf circumference), eating difficulties, and presence of clinical signs ofUN. MEONF-II data were analysed by Receiver Operating Characteristics (ROC) curves and the area under the curve (AUC); optimal cut-offs were identified by the Youden index (J=sensitivity+specificity–1).
According to the MEONF-II, 41% were at moderate or high UN risk and according to the MNA, 50% were at risk or already undernourished. The suggested cut-off scores were supported by the Youden indices. The lower cut-off for MEONF-II, used to identify any level of risk for UN (>2; J=0.52) gave an overall accuracy of 76% and the AUC was 80%. The higher cut-off for identifying those with high risk for UN (>4; J=0.33) had an accuracy of 63% and the AUC was 70%.
The suggested MEONF-II cut-off scores were statistically supported. This improves the confidence of its clinical use.
PMCID: PMC3149411  PMID: 21814520
cut-off scores; MEOF; MNA; MEONF; nutritional screening; ROC-curve
5.  Validity and user-friendliness of the minimal eating observation and nutrition form – version II (MEONF – II) for undernutrition risk screening 
Food & Nutrition Research  2011;55:10.3402/fnr.v55i0.5801.
To analyze the criterion-related validity and user-friendliness of the Minimal Eating Observation and Nutrition Form – Version II (MEONF – II) and Malnutrition Universal Screening Tool (MUST) in relation to the Mini Nutritional Assessment (MNA). In addition, the effect of substituting body mass index (BMI) with calf circumference (CC) was explored for the MEONF-II.
The study included 100 patients who were assessed for nutritional status with the MNA (full version), considered here to be the gold standard, and screened with the MUST and the MEONF-II. The MEONF-II includes assessments of involuntary weight loss, BMI (or calf circumference), eating difficulties, and presence of clinical signs of undernutrition.
The MEONF-II sensitivity (0.73) and specificity (0.88) were acceptable. Sensitivity and specificity for the MUST were 0.57 and 0.93, respectively. Replacing the BMI with CC in the MEONF-II gave similar results (sensitivity 0.68, specificity 0.90). Assessors considered MEONF-II instructions and items to be relevant, easy to understand and complete (100%), and the questions to be relevant (98%). MEONF-II and MUST took 8.8 and 4.7 minutes to complete, respectively, and both were considered relevant and easy to finish. In addition, MEONF-II was thought to reveal problems that allows for nursing interventions.
The MEONF-II is an easy to use, relatively quick, and sensitive screening tool to assess risk of undernutrition among hospital inpatients, which allows for substituting BMI with CC in situations where measures of patient height and weight cannot be easily obtained. High sensitivity is of primary concern in nutritional screening and the MEONF-II outperforms the MUST in this regard.
PMCID: PMC3021369  PMID: 21246022
undernutrition; screening; criterion-related validity; acceptability; MEOF; MNA; MUST; MEONF
6.  Measurement properties of the Minimal Insomnia Symptom Scale (MISS) in an elderly population in Sweden 
BMC Geriatrics  2010;10:84.
Insomnia is common among elderly people and associated with poor health. The Minimal Insomnia Symptom Scale (MISS) is a three item screening instrument that has been found to be psychometrically sound and capable of identifying insomnia in the general population (20-64 years). However, its measurement properties have not been studied in an elderly population. Our aim was to test the measurement properties of the MISS among people aged 65 + in Sweden, by replicating the original study in an elderly sample.
Data from a cross-sectional survey of 548 elderly individuals were analysed in terms of assumptions of summation of items, floor/ceiling effects, reliability and optimal cut-off score by means of ROC-curve analysis and compared with self-reported insomnia criteria.
Corrected item-total correlations ranged between 0.64-0.70, floor/ceiling effects were 6.6/0.6% and reliability was 0.81. ROC analysis identified the optimal cut-off score as ≥7 (sensitivity, 0.93; specificity, 0.84; positive/negative predictive values, 0.256/0.995). Using this cut-off score, the prevalence of insomnia in the study sample was 21.7% and most frequent among women and the oldest old.
Data support the measurement properties of the MISS as a possible insomnia screening instrument for elderly persons. This study make evident that the MISS is useful for identifying elderly people with insomnia-like sleep problems. Further studies are needed to assess its usefulness in identifying clinically defined insomnia.
PMCID: PMC2994866  PMID: 21054878
7.  The 39 item Parkinson's disease questionnaire (PDQ‐39) revisited: implications for evidence based medicine 
The 39 item Parkinson's disease questionnaire (PDQ‐39) is the most widely used patient reported rating scale in Parkinson's disease. However, several fundamental measurement assumptions necessary for confident use and interpretation of the eight PDQ‐39 scales have not been fully addressed.
Postal survey PDQ‐39 data from 202 people with Parkinson's disease (54% men; mean age 70 years) were analysed regarding psychometric properties using traditional and Rasch measurement methods.
Data quality was good (mean missing item responses, 2%) and there was general support for the legitimacy of summing items within scales without weighting or standardisation. Score reliabilities were adequate (Cronbach's alpha 0.72–0.95; test–retest 0.76–0.93). The validity of the current grouping of items into scales was not supported by scaling success rates (mean 56.2%), or factor and Rasch analyses. All scales represented more health problems than that experienced by the sample (mean floor effect 15%) and showed compromised score precision towards the less severe end.
Our results provide general support for the acceptability and reliability of the PDQ‐39. However, they also demonstrate limitations that have implications for the use of the PDQ‐39 in clinical research. The grouping of items into scales appears overly complex and the meaning of scale scores is unclear, which hampers their interpretation. Suboptimal targeting limits measurement precision and, therefore, probably also responsiveness. These observations have implications for the role of the PDQ‐39 in clinical trials and evidence based medicine. PDQ‐39 derived endpoints should be interpreted and selected cautiously, particularly regarding small but clinically important effects among people with less severe problems.
PMCID: PMC2117601  PMID: 17442762
8.  Assessment of fall-related self-efficacy and activity avoidance in people with Parkinson's disease 
BMC Geriatrics  2010;10:78.
Fear of falling (FOF) is common in Parkinson's disease (PD), and it is considered a vital aspect of comprehensive balance assessment in PD. FOF can be conceptualized differently. The Falls-Efficacy Scale (FES) assesses fall-related self-efficacy, whereas the Survey of Activities and Fear of Falling in the Elderly (SAFFE) assesses activity avoidance due to the risk of falling. This study aimed at investigating the validity and reliability of FES and SAFFE in people with PD.
Seventy-nine people with PD (mean age; 64 years, SD 7.2) completed the Swedish version of FES(S), SAFFE and the physical functioning (PF) scale of the 36-Item Short-Form Health Survey (SF-36). FES(S) and SAFFE were administered twice, with an 8.8 (SD 2.3) days interval. Assumptions for summing item scores into total scores were examined and score reliability (Cronbach's alpha and test-retest reliability) were calculated. Construct validity was assessed by examining the pattern of Spearman correlations (rs) between the FES(S)/SAFFE and other variables, and by examining differences in FES(S)/SAFFE scores between fallers and non-fallers, genders, and between those reporting FOF and unsteadiness while turning.
For both scales, item mean scores (and standard deviations) were roughly similar and corrected item-total correlations exceeded 0.4. Reliabilities were ≥0.87. FES(S)-scores correlated strongest (rs, -0.74, p < 0.001) with SAFFE-scores, whereas SAFFE-scores correlated strongest with PF-scores (rs, -0.76, p < 0.001). Both scales correlated weakest with age (rs ≤ 0.08). Experiencing falls, unsteadiness while turning, and FOF was associated with lower fall-related self-efficacy and higher activity avoidance.
This study provides initial support for the score reliability and validity of the FES(S) and SAFFE in people with PD.
PMCID: PMC2984450  PMID: 20973974
9.  Psychometric properties of the DISABKIDS Chronic Generic Module (DCGM-37) when used in children undergoing treatment for cancer 
The aim was to evaluate data quality and psychometric properties of an instrument for measurement of health-related quality of life: DISABKIDS Chronic Generic Module (DCGM-37) used in school-aged children with cancer.
All school-children diagnosed with cancer in Sweden during a two-and-a-half year period were invited to participate in the study. Analysis was performed on combined data from two assessments, two and-a-half and five months after start of cancer treatment (n = 170). The instrument was examined with respect to feasibility, data quality, reliability and construct and criterion-based validity.
Missing items per dimension ranged from 0 to 5.3 percent, with a majority below three percent. Cronbach's alpha values exceeded 0.70 for all dimensions. There was support for the suggested groupings of items into dimensions for all but six of the 36 items of the DCGM-37 included in this study. The instrument discriminated satisfactorily between diagnoses reflecting treatment burden.
The results indicate satisfactory data quality and reliability of the DCGM-37 when used in children undergoing treatment for cancer. Evaluation of construct validity showed generally acceptable results, although not entirely supporting the suggested dimensionality. Continued psychometric evaluation in a larger sample of children during and after treatment for cancer is recommended.
PMCID: PMC2955689  PMID: 20920171
10.  Development and testing of a self administered version of the Freezing of Gait Questionnaire 
BMC Neurology  2010;10:85.
The Freezing of Gait Questionnaire (FOGQ) was developed in response to the difficulties of observing and quantifying freezing of gait (FOG) clinically as well as in laboratory settings. However, as the FOGQ is a clinician-administered patient-reported rating scale it cannot be used in postal surveys. Here we report the development and measurement properties of a self-administered version of the FOGQ (FOGQsa).
A clinical sample and a postal survey sample of non-demented people with Parkinson's disease (PD; total n = 225) completed the FOGQsa and questionnaires concerning physical functioning (PF) and fall-related self efficacy (FES). Additional questions (No/Yes) regarded previous falls and whether they were afraid of falling. The clinical sample was also assessed with the Unified PD Rating Scale (UPDRS). Thirty-five participants completed FOGQsa and were also assessed with the original version (FOGQ) in a clinical interview.
There were no differences (P = 0.12) between FOGQ (median, 10; q1-q3, 2-14) and FOGQsa (median, 8; 2-14) scores. The Spearman (rs) and intra-class correlations between the two were 0.92 and 0.91 (95% CI, 0.82-0.95), respectively. For FOGQsa, corrected item-total correlations ranged between 0.68-0.89. Reliability was 0.93 (95% CI, 0.91-0.94). FOGQsa scores correlated strongest with UPDRS Item 14 (Freezing; rs, 0.76) and with FES (rs, -0.74). The weakest correlation was found with age (rs, 0.14). Fallers scored significantly (p < 0.001) higher on FOGQsa compared to non-fallers, median scores 8 (q1-q3, 4-14) versus 2 (0-7). Those expressing a fear of falling scored higher (p < 0.001) than those who did not, median scores 2 (0-7) versus 6 (2-14).
The present findings indicate that the FOGQsa is as reliable and valid as the original interview administered FOGQ version. This has important clinical implications when investigating FOG in large scale studies.
PMCID: PMC2955563  PMID: 20863392
11.  Uncovering Indicators of the International Classification of Functioning, Disability, and Health from the 39-Item Parkinson's Disease Questionnaire  
Parkinson's Disease  2010;2010:984673.
The 39-item Parkinson's disease questionnaire (PDQ-39) is the most widely used patient-reported rating scale in Parkinson's disease (PD). However, recent studies have questioned its validity and it is unclear what scores represent. This study explored the possibility of regrouping PDQ-39 items into scales representing the International Classification of Functioning, Disability, and Health (ICF) components of Body Functions and Structures (BF), Activities and Participation (AP), and Environmental (E) factors. An iterative process using Rasch analysis produced five new items sets, two each for the BF and AP components and one representing E. Four of these were found to represent clinically meaningful variables: Emotional Impairment (BF), Gross Motor Disability (AP), Fine Motor Disability (AP), and Socioattitudinal Environment (E) with acceptable reliability (0.73–0.96) and fit to the Rasch model (total item-trait chi-square, 8.28–33.2; P > .05). These new ICF-based scales offer a means to reanalyze PDQ-39 data from an ICF perspective and to study its health components using a widely available health status questionnaire for people with PD.
PMCID: PMC2957468  PMID: 20976013
12.  Interpretation of response categories in patient-reported rating scales: a controlled study among people with Parkinson's disease 
Unambiguous interpretation of ordered rating scale response categories requires distinct meanings of category labels. Also, summation of item responses into total scores assumes equal intervals between categories. While studies have identified problems with rating scale response category functioning there is a paucity of empirical studies regarding how respondents interpret response categories. We investigated the interpretation of commonly used rating scale response categories and attempted to identify distinct and roughly equally spaced response categories for patient-reported rating scales in Parkinson's disease (PD) and age-matched control subjects.
Twenty-one rating scale response categories representing frequency, intensity and level of agreement were presented in random order to 51 people with PD (36 men; mean age, 66 years) and 36 age-matched controls (14 men; mean age, 66). Respondents indicated their interpretation of each category on 100-mm visual analog scales (VAS) anchored by Never - Always, Not at all - Extremely, and Totally disagree - Completely agree. VAS values were compared between groups, and response categories with mean values and non-overlapping 95% CIs corresponding to equally spaced locations on the VAS line were sought to identify the best options for three-, four-, five-, and six-category scales.
VAS values did not differ between the PD and control samples (P = 0.286) or according to educational level (P = 0.220), age (P = 0.220), self-reported physical functioning (P = 0.501) and mental health (P = 0.238), or (for the PD sample) PD duration (P = 0.213) or presence of dyskinesias (P = 0.212). Attempts to identify roughly equally spaced response categories for three-, four-, five-, and six-category scales were unsuccessful, as the 95% CIs of one or several of the identified response categories failed to include the criterion values for equal distances.
This study offers an evidence base for selecting more interpretable patient-reported rating scale response categories. However, problems associated with raw rating scale data, primarily related to their ordinal structure also became apparent. This argues for the application of methodologies such as Rasch measurement. Rating scale response categories need to be treated with rigour in the construction and analysis of rating scales.
PMCID: PMC2908570  PMID: 20576159
13.  Self‐reported health in people with Parkinson's disease left untreated at diagnosis 
Early initiation of treatment in Parkinson's disease prevents patient‐reported deteriorations, but what is gained?
PMCID: PMC2117842  PMID: 17135458
14.  The 39-Item Parkinson's Disease Questionnaire (PDQ-39): Is it a Unidimensional Construct? 
The 39-item Parkinson's Disease Questionnaire, and particularly its summary index (PDQ-39SI) is a widely used patient-reported clinical trial endpoint. A basic assumption when summing items into a total score is that they represent a common variable. We therefore assessed the unidimensionality of the PDQ-39SI using Rasch and confirmatory factor analysis. Both analyses showed model misfit. Adjustment for differential item functioning and disordered response category thresholds did not improve model fit, and residual analyses showed deviation from unidimensionality. These data indicate multidimensionality and challenge the interpretation and validity of PDQ-39SI scores. Clinicians and investigators should use and interpret the PDQ-39SI with caution.
PMCID: PMC3002633  PMID: 21179529
dimensionality; outcome measurement; quality of life; Parkinson's disease
15.  Cross-diagnostic validity of the Nottingham health profile index of distress (NHPD) 
The Nottingham Health Profile index of Distress (NHPD) has been proposed as a generic undimensional 24-item measure of illness-related distress that is embedded in the Nottingham Health Profile (NHP). Data indicate that the NHPD may have psychometric advantages to the 6-dimensional NHP profile scores. Detailed psychometric evaluations are, however, lacking. Furthermore, to support the validity of the generic property of outcome measures evidence that scores can be interpreted in the same manner in different diagnostic groups are needed. It is currently unknown if NHPD scores have the same meaning across patient populations. This study evaluated the measurement properties and cross-diagnostic validity of the NHPD as a survey instrument among people with Parkinson's disease (PD) and peripheral arterial disease (PAD).
Data from 215 (PD) and 258 (PAD) people were Rasch analyzed regarding model fit, reliability, differential item functioning (DIF), unidimensionality and targeting. In cases of cross-diagnostic DIF this was adjusted for and the impact of DIF on the total score and person measures was assessed.
The NHPD was found to have good overall and individual item fit in both disorders as well as in the pooled sample, but seven items displayed signs of cross-diagnostic DIF. Following adjustment for DIF some aspects of model fit were slightly compromised, whereas others improved somewhat. DIF did not impact total NHPD scores or resulting person measures, but the unadjusted scale displayed minor signs of multidimensionality. Reliability was > 0.8 in all within- and cross-diagnostic analyses. Items tended to represent more distress (mean, 0 logits) than that experienced by the sample (mean, -1.6 logits).
This study supports the within- and cross-diagnostic validity of the NHPD as a survey tool among people with PD and PAD. We encourage others to reassess available NHP data within the NHPD framework to further evaluate the strengths and weaknesses of this simple patient-reported index of illness-related distress.
PMCID: PMC2483964  PMID: 18597691

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