Constraint-induced movement therapy.
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Biomedical subjects
Publications and source records attributed to L M Bouter.
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BACKGROUND: Conducting a pragmatic randomised trial in primary care is often accompanied by practical problems. Such problems are seldom reported and may constitute useful lessons for researchers planning future trials. AIM: To address the difficulties involved in patient recruitment and to present measures to minimise bias during outcome assessment. METHOD: A recently conducted trial comparing the effects of corticosteroid injections and physiotherapy for painful stiff shoulder was used to illustrate problems related to patient recruitment and outcome assessment. RESULTS: Recruitment of patients was not without difficulties despite careful preparation. Recruitment was discontinued after 20 months, when 109 of the intended 120 patients had been admitted to the trial. The shoulder trial mainly included patient-oriented subjective outcome measures. Subgroup analyses demonstrated that patient preferences might have had some influence on outcome. CONCLUSIONS: General practitioners might be willing or unwilling to participate in research for many reasons. The researcher should take these motivations into account when inviting physicians to take part in research. Strategies to enhance enrolment should be prepared before the start of the trial. When blinding of patients is problematic, patient preferences should be assessed before randomisation and their influence on the outcome studied. Although involving a blinded independent observer enables a more objective assessment of outcome, the success of blinding should be clearly evaluated.
Baroreflex sensitivity (BRS) has been proposed as a diagnostic parameter for neurological disorders and as a survival-prognosis parameter in diabetic and cardiac patients. Therefore reference values and the reproducibility of BRS were assessed, taking into account the possible influence of age, gender, test conditions and some analysis variants. Healthy subjects (n=191) were randomly selected from the 50-75-year-old general population (the Hoorn Study). Variations in blood pressure and heart rate were recorded non-invasively during three breathing modes: spontaneous (3 min), slow metronome (1 min; 6 breaths/min=0.1 Hz) and fast metronome (1 min; 15 breaths/min=0.25 Hz), all in a supine position. From these recordings, BRS was assessed as the transfer gain between changes in blood pressure and heart period, and as the alpha coefficient. BRS values ranged from 5.0 to 8.9 ms.mmHg(-1). Slow metronome breathing resulted in higher BRS values than fast breathing, while during spontaneous breathing BRS in the low-frequency band was lower than that in the high-frequency band (respiratory origin). BRS values decreased with lower coherence criteria. BRS-alpha was significantly higher than BRS-gain. While regression analysis showed no gender differences, BRS decreased with age. Therefore age-specific reference values were calculated. The reproducibility of BRS values was in general moderate, with reliability coefficients ranging from 43 to 81% and coefficients of variation ranging from 34 to 59%. In conclusion, this study shows age, breathing mode, frequency and coherence threshold to affect measures of BRS. Therefore these factors should be considered in clinical studies; appropriate reference values are given.
To assess current satisfaction with paediatric team conferences in the Netherlands and identify aspects eligible for future improvement, an open-response questionnaire was sent to a representative of each paediatric rehabilitation setting in the Netherlands. Questions were asked regarding the organization and effectiveness of current team conferences and aspects eligible for improvement. Furthermore, rehabilitation professionals of these settings were asked to fill in a structured questionnaire on their satisfaction with the team conferences (the satisfaction measure, SM). Two types of team conferences are distinguished, namely (1) evaluative conferences and (2) urgent problem conferences. In the open-response questionnaire, all representatives (n = 20) indicated that they find the team conferences effective. Rehabilitation professionals (n = 165) are only moderately satisfied, as indicated by the scores on the SM (scores range from 2.99 to 3.78 on a scale from 1 (= very dissatisfied) to 5 (= very satisfied). All but one representative identified aspects of the conference that they would like to improve. Representatives recommended improvement of (1) the preparation of the conference by using a clear and uniform structured report form (n = 8), (2) the conference itself by concentrating on major discussion points and treatment goals (n = 10), and (3) the outcome of the conference by formulating interdisciplinary treatment goals (n = 7). Results indicate that there is a need and also possibilities for improvement of team conferences in paediatric rehabilitation.
CONTEXT: Human adipose tissue expresses and releases the proinflammatory cytokine interleukin 6, potentially inducing low-grade systemic inflammation in persons with excess body fat. OBJECTIVE: To test whether overweight and obesity are associated with low-grade systemic inflammation as measured by serum C-reactive protein (CRP) level. DESIGN AND SETTING: The Third National Health and Nutrition Examination Survey, representative of the US population from 1988 to 1994. PARTICIPANTS: A total of 16616 men and nonpregnant women aged 17 years or older. MAIN OUTCOME MEASURES: Elevated CRP level of 0.22 mg/dL or more and a more stringent clinically raised CRP level of more than 1.00 mg/dL. RESULTS: Elevated CRP levels and clinically raised CRP levels were present in 27.6% and 6.7% of the population, respectively. Both overweight (body mass index [BMI], 25-29.9 kg/m2) and obese (BMI, > or =30 kg/m2) persons were more likely to have elevated CRP levels than their normal-weight counterparts (BMI, <25 kg/m2). After adjustment for potential confounders, including smoking and health status, the odds ratio (OR) for elevated CRP was 2.13 (95% confidence interval [CI], 1.56-2.91) for obese men and 6.21 (95% CI, 4.94-7.81) for obese women. In addition, BMI was associated with clinically raised CRP levels in women, with an OR of 4.76 (95% CI, 3.42-6.61) for obese women. Waist-to-hip ratio was positively associated with both elevated and clinically raised CRP levels, independent of BMI. Restricting the analyses to young adults (aged 17-39 years) and excluding smokers, persons with inflammatory disease, cardiovascular disease, or diabetes mellitus and estrogen users did not change the main findings. CONCLUSION: Higher BMI is associated with higher CRP concentrations, even among young adults aged 17 to 39 years. These findings suggest a state of low-grade systemic inflammation in overweight and obese persons.
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Meta-analysis comprises the analysis of the data of similar studies gathered in a systematic review. If the results of the studies differ (strongly), this is called heterogeneity. Possible causes of heterogeneity are: a wrong choice of type of measure of treatment effect, differences of methodological quality between studies, or real differences between studies. Heterogeneity between studies can be assessed by thorough examination of the differences between study characteristics in combination with a visual inspection of the degree of overlap of the confidence intervals of the estimates of effect of the different studies. By applying the random effects model for pooling, (non-systematic) heterogeneity between studies can be addressed. In case of heterogeneity between studies, sources of heterogeneity should be explored by means of subgroup analysis according to strict, present criteria. Subgroup analysis should address subgroups of patients within studies.
Meta-analysis comprises the analysis of the data gathered in a systematic review. Meta-analysis can be defined as the combination of pooling results of similar studies into one overall estimate of the effect on the one hand and the exploration of sources of heterogeneity between studies on the other. A general statistical model is available for pooling the estimates of various types of effect parameters. Pooling enables the estimation of the effect of an intervention or exposure as precisely as possible (with narrow confidence intervals) which allows detection of minor effects. The Mantel-Haenszel method is also an excellent method for pooling effect parameters of dichotomous outcomes. Pooling provides an efficient means of summarizing the available knowledge.
The methodological quality of the primary studies included in a systematic review may influence its results and final conclusions. Methodological quality may be defined in various ways. Partially because of this there are many different assessment lists. The most important dimension of quality is internal validity, defined as the confidence that the design, performance and report of a trial prevent or reduce systematic errors (bias) in the outcomes. For only a limited number of internal validity items a relationship with bias has been proven in empirical studies: concealment of randomisation and blinding of patients and outcome assessors. Preferably, quality should be assessed by at least 2 assessors independently. There is no consensus whether assessment should be done blinded for authors, journal, results and conclusions. Internal validity can be incorporated into statistical pooling in various ways: as a selection criterion, to be used as weight or to hierarchically order studies in a presentation. Well-designed comparative studies are needed to provide clearer guidelines for methodological assessment in the future.
Structured searching and selection of studies is an important component of a systematic review. It is recommended to record the various steps in a protocol in advance. The thoroughness of the searching and selection will partially depend on the available resources, like manpower and funds. A search action should be based on an unequivocally formulated research or clinical question, that is operationalized into clear inclusion and exclusion criteria. The actual start of a search strategy is a search in preferably multiple databases like Medline and EMBASE-Excerpta Medica. Additional search actions can be performed in trial registers and printed indexes and by correspondence with experts and hand searching of journals. Storage of the search results in a bibliographic database is recommended. Various methodological problems may play a role in searching and selecting studies for a review: studies may selectively not be published, results are only partially presented in the publication, studies are selectively included in reference lists, and reviewers themselves may make systematic errors in the selection process.
In subjects with impaired glucose tolerance hyperproinsulinaemia has been shown to be predictive for progression to Type II (non-insulin-dependent) diabetes mellitus. These findings are often interpreted as early indicators of an impaired beta-cell function. The aim of our study was to assess the potential determinants of hyperproinsulinaemia in subjects with impaired glucose tolerance. The study group consisted of 110 subjects, 45-74 years of age with mean 2 h plasma glucose concentrations between 8.6 and 11.1 mmol/l following two oral glucose tolerance tests. Subsequently, the hyperglycaemic clamp technique (10 mmol/l, with a priming infusion of 20% glucose solution, 150 mg/kg) was used to assess the beta-cell function (time needed to reach the insulin peak) and insulin sensitivity (M/I value: glucose metabolised divided by insulin response, 150-180 min). Results showed that the intact-proinsulin:insulin ratio increased with increasing time needed to reach the insulin peak (0.065, 0.079 and 0.101; time needed to reach the insulin peak < or = 5 min, 5 to 15 min, > 15 min; p < 0.05). The split-proinsulin:insulin ratio showed a similar association with the time needed to reach the insulin peak. These associations were independent of age, sex, body mass index and waist:hip ratio. In conclusion, this study shows that relative hyperproinsulinaemia is associated with an impaired beta-cell function in a study group of subjects with impaired glucose tolerance selected after two oral glucose tolerance tests.
AIMS/HYPOTHESIS: The degree of glycaemia has been shown to be associated with all-cause and cardiovascular mortality in diabetic subjects. Whether this association also exists in the general population is still controversial. We studied the predictive value of fasting plasma glucose, 2-hour post-load glucose and HbA1c in a population-based cohort of 2363 older (50-75 years) subjects, without known diabetes. METHODS: Relative risks (RR) of all-cause and cardiovascular mortality were estimated by Cox proportional hazards model, adjusting for age and sex, and additionally for known cardiovascular risk factors. RESULTS: During 8 years of follow-up, 185 subjects died; 98 of cardiovascular causes. Fasting plasma glucose was only predictive in the diabetic range, although the risks started to increase at about 6.1 mmol/l. Post-load glucose and HbA1c values were, even within the non-diabetic range, associated with an increased risk (p for linear trend < 0.05). These increased risks were mostly, but not completely, attributable to known cardiovascular risk factors. After exclusion of subjects with newly diagnosed diabetes or with pre-existent cardiovascular disease (n = 551), a 5.8 mmol/l increase of post-load glucose (corresponding to two standard deviations of the population distribution) was associated with a higher age-adjusted and sex-adjusted risk of all-cause (RR 2.24) and cardiovascular mortality (RR 3.40) (p < 0.05). After additional adjustment for known cardiovascular risk factors, these relative risks were still statistically significant, with values of 2.20 and 3.00 respectively (p < 0.05). CONCLUSION/INTERPRETATION: High glycaemic variables, especially 2-h post-load glucose concentrations and to a lesser extent HbA1c values, indicate a risk of all-cause and cardiovascular mortality in a general population without known diabetes.
In this prospective study we investigated the predictive value of quantitative ultrasound (QUS) measurements and other potential predictors of osteoporotic fractures in the elderly. During a 1-year period, 710 participants (132 men and 578 women), aged 70 years and older (mean age +/- SD: 82.8 +/- 5.9), were recruited from seven homes and apartment houses for the elderly. QUS measurements (broadband ultrasound attenuation (BUA) and speed of sound (SOS)) were assessed with a clinical bone densitometer. A structured questionnaire was used to collect information on other potential predictors. Follow-up of fractures was done each half year by telephone interviews. During the study period (median follow-up 2.8 years, maximum 3.7 years), 30 participants had a first hip fracture and 54 suffered from a first other nonspinal fracture. Cox regression analyses, adjusted for age and sex, showed that the relative risk (RR) of hip fracture for each standard deviation reduction was 2.3 (95% CI, 1.4-3.7) for BUA and 1.6 (95% CI, 1.1-2.3) for SOS. Slightly weaker relationships were found for any fracture (BUA: RR, 1.6; 95% CI, 1.2-2.1; SOS: RR, 1.3; 95% CI, 1.0-1.6). Multivariable analyses identified low BUA values and immobility as the strongest predictors for hip fractures and any fracture. Female gender proved to be the strongest predictor for other nonspinal fractures. It can be concluded that QUS measurements can predict the risk for hip fracture and any fracture in elderly people.
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In this study we estimated the indirect costs of back pain in 1991 in The Netherlands on the basis of two approaches: the traditionally used human capital method and the more recently developed friction cost method. The indirect costs of illness were defined as the value of production losses of paid labour and related costs to society due to back pain. The results of this study in 1991 in The Netherlands show that the short-term indirect costs estimated by the human capital method were more than three times as high as the indirect costs estimated by the friction cost method (US$ 4.6 billion vs. USS 1.5 billion, respectively). The lower estimate of indirect costs when using the friction cost method is mainly due to the fact that in this method actual production losses are estimated during a relatively short friction period, which is defined as the period needed to restore the initial production level. In contrast with the human capital method, long-term absenteeism and disability do not induce additional costs when applying the friction cost method. Since the friction cost method takes into account that employees can be replaced, we believe that this method produces a more accurate estimate of indirect costs than the human capital method. Notwithstanding the resulting decrease in indirect costs of back pain, these costs are still impressive, representing 0.28% of the GNP in The Netherlands in 1991. As a consequence, but particularly stimulated by structural changes in the Dutch social security system, policies aimed at reducing indirect costs of back pain, increasingly concentrate on the development and evaluation of interventions early after the onset of disease. This is complemented, on the one hand, by the development of clinical guidelines for the management of back pain in primary care and, on the other hand, by governmental policies aimed at reintegration of chronically ill in the labour force.
The objective of this study was to compare the responsiveness and assess the concurrent validity of two functional health status instruments, the Dartmouth COOP charts and the SF-36 in chronic low-back pain (CLBP) patients. The data came from 129 of 174 patients who participated in a randomized clinical trial of the therapeutic management of CLBP. Reliable and valid disease-specific outcomes, patient-rated low-back pain and disability, were used as external criteria (EC) to identify improved and non-improved patients. Unpaired t-statistics and receiver operating characteristic (ROC) curve calculations were used to quantify responsiveness. The two instruments had sufficient and very similar responsiveness using both EC. Comparisons between improved and non-improved patients for the COOP charts and SF-36, respectively, using pain as EC, yielded differences which translated into large effect sizes (0.8 and 0.7) (P=0.0008 and 0.003). Using disability as EC, differences of moderate effect size were found (0.5 and 0.6) (P=0.02 and 0.002). The ROC curve calculations using pain as EC resulted in areas under the curve of 0.76 (95% CI: 0.64, 0.88) for the COOP charts, and 0.74 (95% CI: 0.60, 0.88) for the SF-36. The corresponding areas using disability as EC were 0.67 (95% CI: 0.55, 0.79) and 0.72 (95% CI: 0.60, 0.84). The best cut-off point in both instruments for differentiating between improved and non-improved patients was approximately six percentage points. The constructs of functional health status, as reflected in the global scores of the two instruments, are highly correlated (r=0.82). Six of the instruments' nine dimensions are moderately to highly correlated (r=0.52 to 0.86), and the overall canonical correlation was high (R=0.9). In conclusion, both instruments seem equally suitable for use as outcome measures in clinical trials on CLBP. The COOP charts are faster to fill out and score.
OBJECTIVE: This study examined whether dementia patients with greater cognitive reserve had increased mortality rates, and whether this association was different across strata of cognition, functional ability and depression. METHODS: In the community-based Amsterdam Study of the Elderly, 261 non-institutionalized dementia patients, identified using the Geriatric Mental State Schedule (GMS), were followed for an average of 55.5 months after which mortality data were obtained. Cognitive reserve was indicated by years of education and pre-morbid intelligence (measured using the Dutch Adult Reading Test). Cognition, functional ability and depression were indicated by Mini-Mental State scores, ADL and IADL measurements and GMS depressive syndrome, respectively. RESULTS: During the follow-up 146 persons (55.9%) died. Cox regression analyses showed that more highly educated dementia patients had higher mortality rates, only if they had low MMSE scores or if they had a concurrent depression. Pre-morbid intelligence was associated with a higher mortality rate, independent of cognition, but this association was much stronger among patients with depression. The positive association between education or intelligence and mortality was not modified by functional disabilities. CONCLUSIONS: The results suggest that dementia patients with greater cognitive reserve have increased mortality rates, only if the disease has progressed to such an extent that clinical symptoms are more severe. In this respect, the reserve hypothesis needs a modification. Depression in dementia patients with greater cognitive reserve may reflect a subgroup of patients with poor prognosis.
OBJECTIVES: Mild hyperhomocysteinaemia (HHC), fasting or after methionine loading, is associated with an increased risk and severity of atherosclerotic vascular disease. Post-methionine and fasting HHC are responsive to treatment with vitamin B, and folic acid. We performed a prospective cohort study amongst normohomocysteinaemic and vitamin-treated (vitamin B6, 250 mg plus folic acid, 5 mg daily) hyperhomocysteinaemic patients with premature peripheral arterial occlusive disease and assessed the incidence of cardiovascular events. DESIGN: We studied 273 consecutive patients with clinically manifest peripheral arterial occlusive disease with onset before the age of 56, 79 (28.9%) of whom had postmethionine HHC. Follow-up was obtained in 232 (85'%o) patients. At baseline, 70 (30')/) were hyperhomocysteinaemic after methionine loading and started treatment with vitamin B, and folic acid; 162 (70%) were normohomocysteinaemic (reference group). RESULTS: During the follow-up period (median 20, range 1-63 months), 48 (29.6%) and 23 (32.9%) of the normo- and the hyperhomocysteinaemic patients, respectively, had a new cardiovascular event. Most (75%) involved the peripheral arterial system. The crude incidence rate for any cardiovascular event was 0.16 (95% CI, 0.12-0.21) per person per year in the normohomocysteinaemic and 0.16 (95% CI, 0.09-0.22) per person per year in the hyperhomocysteinaemic group. Multivariate Cox regression analyses showed that higher plasma homocysteine levels were associated with an increased risk of new cardiovascular events in the normohomocysteinaemic patients (relative risk [RR] per 1 micromol L(-1), 1.17 [CI, 1.05-1.30] for fasting and 1.06 [CI, 1.01-1.12] for postmethionine levels), but not in the hyperhomocysteinaemic (vitamin-treated) patients. The adjusted RR for new cardiovascular events in the hyper- as compared to the normohomocysteinaemic patients was 0.76 (CI, 0.33-1.74). CONCLUSIONS: These data are consistent with a protective effect of treatment with vitamin B6 and folic acid in patients with premature peripheral arterial occlusive disease and postmethionine HHC. Double-blind randomized trials are necessary to confirm this.