Biomedical subjects

André L M Verbeek

Publications and source records attributed to André L M Verbeek.

At least 19 recordsLinked to original sources

PubMed2007

Effect of routine follow-up after treatment for laryngeal cancer on life expectancy and mortality: results of a Markov model analysis.

BACKGROUND: Routine follow-up is offered to all patients with laryngeal cancer who are treated with curative intent. Although time and resources are devoted to surveillance, the effect of asymptomatic recurrence detection is not well understood. For this study, the authors evaluated the effect that routine follow-up may have on life expectancy and disease-specific mortality rate for patients with laryngeal cancer. METHODS: Using a Markov model, a cohort simulation was performed on 4 hypothetical age groups of patients with laryngeal cancer. Three different follow-up strategies were compared-the current schedule, no follow-up, and the perfect follow-up-in which all recurrences were detected asymptomatically. Sensitivity analyses were performed to study the impact of variations in the transition rates on life expectancy. RESULTS: Compared with no follow-up, the current schedule showed a gain in life expectancy with a range from 0.3 years to 1.5 years that decreased with advancing age. Abolishing the current follow-up schedule raised the disease-specific mortality rate; the increase ranged from 2.8% to 5.9%. Variations of +/-25% in the transition rates produced only a modest effect on life expectancy. CONCLUSIONS: A small reduction in life expectancy was observed when follow-up was withheld from the majority of patients. Disease-specific mortality rates rose when no follow-up was provided. These rates probably were overestimated. A simplified version of the current follow-up protocol may be implemented.

Adult↗

PubMed2007

Screening for local and regional cancer recurrence in patients curatively treated for laryngeal cancer: definition of a high-risk group and estimation of the lead time.

BACKGROUND: All patients treated for laryngeal cancer are offered the same follow-up schedule to detect asymptomatic locoregional recurrences. In this study, we evaluated the prognostic profile of patients for cancer recurrence and estimated the lead time. METHODS: A cohort study was performed between 1990 and 1995. Cox proportional hazards model was used to analyze the prognostic factors. The effect of altering the follow-up for asymptomatic recurrence detection was determined after estimating the lead time. RESULTS: The variables cT classification, smoking, and histologic grade proved to be prognostic factors. The risk of locoregional failure was 15% in the low-risk group versus 29% in the high-risk group. The estimated lead time was 2 to 4 weeks. CONCLUSION: Risk profiles for locoregional relapse were defined. Intensifying the follow-up schedule is not advisable because the lead time is very short. An excessively high number of routine visits would have to be performed to increase the detection rate for asymptomatic recurrences.

Carcinoma, Squamous Cell↗

PubMed2006

Validity and reproducibility of the Jamar dynamometer in children aged 4-11 years.

PURPOSE: Validity and reproducibility of the Jamar dynamometer were evaluated in children aged 4-11 years. METHOD: Hand grip strength was measured on the dominant side and non-dominant side in 67 patients who had been referred to our specialist centre in the past 3 years because of suspected myopathy. All the patients had had muscle biopsy. Sixteen out of the 67 patients proved to have myopathy, while 51 had no myopathy. The investigator was blinded against the true diagnosis and clinical course of the patients at the time of testing. Validity was assessed by the power to discriminate between patients with and without myopathy, using logistic regression analysis and receiver operating characteristic (ROC) analysis. The area under the ROC curve (AUC) was calculated as a measure of the discriminative power. Sensitivity (Se) and specificity (Sp) were assessed at a specifically chosen cut-off point. Reproducibility was assessed by evaluating the test-retest reliability in a stratified random sample of 40 patients who returned for remeasurements, using the intraclass correlation coefficient (ICC). RESULTS: AUCs ranged from 0.78 - 0.82. At an Se = 81% cut-off point, Sp varied from 67-73%. ICCs ranged from 0.91-0.93. CONCLUSIONS: The Jamar dynamometer had discriminative power in children with suspected myopathy. Reproducibility was high. The Jamar dynamometer was a good, but not completely accurate, test for myopathy.

Area Under Curve↗

PubMed2006

Segregation analysis of urothelial cell carcinoma.

A family history of urothelial cell carcinoma (UCC) confers an almost two-fold increased risk of developing UCC. It is unknown whether (part of) this aggregation of UCC has a Mendelian background. We performed complex segregation analyses on 1193 families ascertained through a proband with UCC of the bladder, ureter, renal pelvis or urethra, who were newly diagnosed between January 1, 1995 and December 31, 1997 and registered by two population-based cancer registries in the southeastern part of the Netherlands. Data were reported on 10 738 first-degree relatives by postal questionnaire; 101 of these relatives had UCC. All reported occurrences of UCC were verified (if possible) using medical records. Analyses were performed with the S.A.G.E. segregation package. Five restricted models (Mendelian dominant, Mendelian recessive, Mendelian co-dominant, 'no major gene' model and environmental model) were tested against the general unrestricted model. Sex and smoking status were incorporated as covariates. Strong evidence of Mendelian inheritance of UCC through a single major gene was not found in these 1 193 families. However, since none of the Mendelian models could be rejected, an inherited subtype of UCC cannot be excluded. A major gene may segregate in some families but this effect may have been masked in a background of high sporadic incidence. The 'no major gene' (or sporadic) model appeared to be the most parsimonious one to describe the occurrence of UCC in these families.

Female↗

PubMed2006

Seventy-five years is an appropriate upper age limit for population-based mammography screening.

In this study, we assessed the results of the Dutch breast cancer screening programme for women aged 70-75, and discussed the current upper age limit of the women invited. We compared the main outcome parameters of the screening programme 1998-2000 for women aged 70-75, with those in women aged 50-69. Breast cancer detection rates were also compared with prediction from 2 variants of a simulation model of breast cancer screening, assuming the mean sojourn time, i.e., the duration of the preclinical detectable phase, to increase or not with age above the age of 65. The underlying idea is that an increase of the sojourn time with age will lead to a less favourable balance between screening benefits and harms from a certain age on. Of the 315,103 women (aged 70-75) invited, 65.6% participated. The attendance increased from 1998 to 2000. For women aged 74 and 75 years, this increase was almost 10%. As a result of the 187,207 screening examinations performed within this age group, 18.3 per 1,000 women were referred and 10.3 per 1,000 breast cancer were diagnosed. Detection rates in both initial and subsequent screens increased steadily with age and got close to those model-simulated rates, which assume a continuously increasing sojourn time with age. A major finding of this study is that the screening participation among elderly women is high. The outcomes of our study suggest a steadily increasing sojourn time of breast tumours beyond the age of 69, leading to a strong increase in detection of cancers, and therefore, disfavouring the balance with the benefits of screening. At present, 75 years of age can be regarded as an appropriate upper age limit for the Dutch programme.

Age Factors↗

PubMed2006

Fear of movement/(re)injury predicting chronic disabling low back pain: a prospective inception cohort study.

STUDY DESIGN: Prospective inception cohort study. OBJECTIVE: To investigate prospectively whether pain-related fear predicts future perceived disability and participation in patients with acute low back pain (LBP). SUMMARY OF BACKGROUND DATA: There are indications that fear of movement/(re)injury, as measured by the Tampa Scale for Kinesiophobia, is present early in an episode of LBP, and that it might be a predictor of future perceived disability and participation. METHODS: A cohort of 555 patients with acute LBP included by general practitioners and physical therapists in primary care settings was followed for 6 months. RESULTS: Results indicate that baseline fear of movement/(re)injury was predictive of future perceived disability and, to a lesser extent (and together with duration and radiation), of participation. CONCLUSIONS: The results suggest that interventions aimed at reducing pain-related fear in the acute stage of LBP might prevent restrictions of activity and participation because of pain, and might be a way of preventing the transition from acute to chronic LBP.

Adult↗

PubMed2006

Cancer recurrence after total laryngectomy: treatment options, survival, and complications.

BACKGROUND: A follow-up schedule to detect asymptomatic cancer recurrence is offered to all patients with laryngeal cancer. In this study, the therapeutic options, prognosis, and morbidity of patients with total laryngectomy, who were found to have cancer recurrence during this follow-up schedule were determined. METHODS: Patients who had undergone a total laryngectomy between January 1, 1990, and January 1, 2000, and had cancer recurrence were included. Data from this group were analyzed retrospectively. RESULTS: The prognosis was poor after the development of cancer recurrence. Curative therapy could only be offered to 27.5% of these patients. Only 5% of the patients were disease free at the end of the study period. Many patients with cancer recurrence needed interventions. A large proportion of them had complications. CONCLUSIONS: The follow-up schedule offered to patients after total laryngectomy should put greater emphasis on care than on early detection of cancer recurrence.

Adult↗

PubMed2006

Validity and reproducibility of a new diagnostic motor performance test in children with suspected myopathy.

To spare more children from painful muscle biopsy, a new non-invasive diagnostic motor performance test is undergoing development. Fifteen functional items were used to measure muscle strength and muscle endurance in 68 patients (47 males, 21 females; mean age 7y 8mo, SD 2y 2mo; range 4 to 11y), who had been referred to our specialist centre in the past 3 years on suspicion of myopathy. All the patients had undergone muscle biopsy. To correct the patients' outcomes for age, sex, and body size, regression prediction equations were obtained from a stratified random sample of 64 normally developing primary-school children aged 4 to 11 years (32 males, 32 females; mean age 8y 1mo, SD 2y 4mo). Feasibility was evaluated on the basis of five criteria. Validity was assessed using logistic regression analysis, receiver operating characteristic analysis, and sensitivity and specificity at a specifically chosen cut-off point. Reproducibility was evaluated by test-retest reliability in a stratified random sample of 40 patients who returned for re-measurements using the intraclass correlation coefficient. Seven items satisfied all five feasibility criteria, had high diagnostic power, and high test-retest reliability. The motor performance test can improve diagnostic procedure in children suspected of having myopathy.

Child↗

PubMed2006

A new motor performance test in a prospective study on children with suspected myopathy.

In the development of a new diagnostic motor performance test to spare more children from painful muscle biopsy, seven functional items were used to measure muscle strength and muscle endurance in a prospective study on new patients. Over a 2-year period, 22 patients (12 males, 10 females; mean age 8y 1mo [SD 2y 6mo], range 4-11y) were recruited for the study. They had all been referred with suspected myopathy. The motor performance test was administered before muscle biopsy. Validity of the seven items was assessed using logistic regression analysis and receiver operating characteristic (ROC) analysis. Two items were withdrawn from the test because they were not suitable for children aged 4 to 5 years. The five remaining items were: Heels, Circuit, Stairs, Jump, and Gowers. A full logistic regression model including these five items was fitted to the total population of 90 patients suspected of having myopathy (from this study and our previous study) to make the best prediction of whether myopathy was present. The ROC area under the curve of the diagnostic prediction model was 0.92 (95% confidence interval [CI] 0.87-0.98) and 0.89 (95% CI 0.87-0.92) after bootstrap correction. This indicated the high diagnostic power that can be expected for future, similar patients. This non-invasive and child-friendly motor performance test can improve diagnostic procedure and, therefore, spare more children from unnecessary muscle biopsy.

Biopsy↗

PubMed2006

Validity and reproducibility of hand-held dynamometry in children aged 4-11 years.

OBJECTIVE: To evaluate validity and reproducibility of hand-held dynamometry in 11 different muscle groups in children. DESIGN AND PATIENTS: Maximum isometric muscle strength was measured with a calibrated hand-held dynamometer in 61 patients aged 4-11 years who had been referred to our specialist centre in the past 3 years because of suspected myopathy. All the patients had had muscle biopsy. METHODS: Validity was assessed by the power to discriminate between patients with and without myopathy, using logistic regression analysis and receiver operating characteristic analysis and sensitivity and specificity at a specifically chosen cut-off point. Reproducibility was evaluated by test-retest reliability in a stratified random sample of 40 patients who returned for re-measurements, using the intraclass correlation coefficient and the standard error of measurement. RESULTS: In the patients, areas under the receiver operating characteristic curve ranged from 0.66 to 0.88. At a specifically chosen cut-off point, sensitivity varied from 73% to 87%, while specificity varied from 54% to 80%. Intraclass correlation coefficients ranged from 0.73 to 0.91. The standard error of measurement ranged from 3.3 N to 12.2 N. CONCLUSION: Performance of hand-held dynamometry varied widely in the 11 muscle groups. Highest performance was observed in the elbow flexors. Test-retest reliability of the mean value of 2 efforts was generally higher than the maximum value.

Child↗

PubMed2006

Fear-avoidance beliefs, disability, and participation in workers and non-workers with acute low back pain.

OBJECTIVES: Fear-avoidance beliefs have been shown to be associated with disability and work status in patients with low back pain. Especially in acute low back pain, much research is needed to increase the knowledge concerning the role of fear-avoidance beliefs and its associated avoidance behavior in the influence on disability and the participation in daily and social life activities. The Fear-Avoidance Beliefs Questionnaire is developed to measure such beliefs and has become increasingly popular for use in primary care practice. The aim of the current study was: 1) to investigate the factor structure of the Fear-Avoidance Beliefs Questionnaire in a population of patients with acute low back pain by means of confirmatory factor analysis; 2) to examine the relationship between fear-avoidance beliefs and perceived disability, as well as participation in daily and social life; and 3) to investigate whether perceived disability mediates the association between pain and participation and between fear-avoidance beliefs and participation. METHODS: The study has a cross-sectional design and was performed on a sample of 615 patients with acute low back pain in primary care settings in The Netherlands. Patients completed a visual analogue scale for pain, the Roland Disability Questionnaire, the Fear-Avoidance Beliefs Questionnaire, a sociodemographic questionnaire, and 5 participation items. RESULTS: Confirmatory factor analysis corroborated the 2-factor structure of the Fear-Avoidance Beliefs Questionnaire as found by Waddell et al. Investigation of the association between fear-avoidance beliefs and perceived disability or participation was performed for workers and non-workers separately. The 2 subscales of the Fear-Avoidance Beliefs Questionnaire were significantly associated with perceived disability and participation, although there were differences between the samples. Perceived disability was significantly predicted by pain intensity and fear-avoidance beliefs. Perceived disability significantly predicted participation, and finally, the mediational role of perceived disability was supported. DISCUSSION: In the early stage of low back pain, the reduction of pain and fear-avoidance beliefs might increase the level of activity, which might foster increased participation in daily and social life activities.

Activities of Daily Living↗

PubMed2005

Acute low back pain: pain-related fear and pain catastrophizing influence physical performance and perceived disability.

Pain-related fear and pain catastrophizing are associated with disability and actual performance in chronic pain patients. In acute low back pain (LBP), little is known about the prediction of actual performance or perceived disability by pain-related fear and pain catastrophizing. This experimental, cross-sectional study aimed at examining whether pain-related fear and pain catastrophizing were associated with actual performance and perceived disability. Ninety six individuals with an episode of acute LBP performed a dynamic lifting task to measure actual performance. Total lifting time was used as outcome measure. The results show that pain-related fear, as measured with the Tampa Scale for Kinesiophobia, was the strongest predictor of this physical task. Using the Roland Disability Questionnaire as a measure of perceived disability, both pain-related fear and pain catastrophizing, as measured with the Pain Catastrophizing Scale, were significantly predictive of perceived disability and more strongly than pain intensity was. The results of the current study suggest that pain-related fear is an important factor influencing daily activities in individuals suffering an episode of acute LBP. The study results have important clinical implications, especially in the development of preventive strategies for chronic LBP.

Acute Disease↗

PubMed2005

Effect of recall rate on earlier screen detection of breast cancers based on the Dutch performance indicators.

BACKGROUND: The recall rate (i.e., the rate at which mammographically screened women are recalled for additional assessment) in the Dutch breast screening program (0.89% in 2000 for subsequent examinations) is the lowest worldwide, with possible consequences including higher rates of late-detected (i.e., "missed") interval and screen-detected cancers. To estimate the effect of changes in recall rate on earlier detection of cancers, we carried out a blinded review of interval and screen-detected cancers in the Dutch screening program. METHODS: A total of 495 sets of screen-negative mammograms (prediagnostic mammogram and the immediate previous mammogram) were collected from women participating in the biennial Dutch screening program. Of these, 250 were from control subjects, and 245 were from women who were subsequently diagnosed with breast cancer (123 interval and 122 screen-detected cancers). These mammograms were read by 15 radiologists who specialize in screening mammography and were blinded to outcome. Mean detection sensitivities for different false-positive rates were calculated using a linear mixed model. These results were used to calculate the effect of recall rate adjustment on earlier detection of cancers and numbers of false-positives. RESULTS: Increasing the recall rate to 2.0% would increase the detection rate from 4.20 per thousand to 4.52 per thousand due to the earlier detection of interval cancers. Moreover, 0.54 per thousand of the screen-detected cancers would be detected 2 years earlier (late screen-detected cancers). At recall rates of 3.0% and 4.0% the detection rate would increase to 4.58 per thousand and 4.63 per thousand, respectively, and 0.64 per thousand and 0.72 per thousand, respectively, of the screen-detected cancers would be detected 2 years earlier. For each 1.0% incremental increase in recall rate above 5.0%, the detection rate would increase by approximately 0.03 per thousand, with positive predictive values decreasing to below 10%. CONCLUSION: Breast cancer can be detected earlier by lowering the threshold for recall, especially for recall rates of 1%-4%. With further recall rate increases, cancer detection levels off with a disproportionate increase of false-positive rates.

Breast Neoplasms↗

PubMed2005

Age at menopause, cause-specific mortality and total life expectancy.

BACKGROUND: A later menopause has been associated with a decreased cardiovascular risk but with an increased risk for breast and endometrial cancer. The net effect on mortality is unclear. We determined the association of age at menopause with longevity and with the balance between cardiovascular and cancer mortality. METHODS: We analyzed data from a breast cancer screening cohort comprising 12,134 postmenopausal women followed for an average of 17 years. We used Cox proportional hazards models and life tables to calculate the life expectancy of an average Dutch woman at age 50. RESULTS: During 204,024 person-years, there were 2607 deaths, of which 963 were due to cardiovascular diseases and 812 due to cancer. Ischemic heart disease risk decreased with a later menopause (hazard ratio [HR] = 0.98 per year; 95% confidence interval = 0.96-0.99), but the risk of fatal uterine or ovarian cancer increased (1.07 per year; 1.01-1.12). A later menopause was associated with longer overall survival; HR for total mortality was 0.98 per year (0.97-0.99). Life expectancy in women with menopause after age 55 was 2.0 years longer than those with menopause before age 40. Adjustment for potential confounders did not materially change the results. CONCLUSIONS: Age-adjusted mortality is reduced 2% with each increasing year of age at menopause. In particular, ischemic heart disease mortality is 2% lower. Although the risk of death from uterine or ovarian cancer is increased by 5%, the net effect of a later menopause is an increased lifespan.

Age Distribution↗

PubMed2004

Value of routine follow-up for patients cured of laryngeal carcinoma.

BACKGROUND: Routine follow-up offered to patients with laryngeal carcinoma in The Netherlands consisted of 22 routine visits over a time period of 10 years after treatment. The primary aims of the follow-up were to detect cancer recurrence in asymptomatic patients and to achieve better survival outcome by reducing cancer-specific mortality rates. METHODS: A longitudinal cohort study was performed to evaluate the effect of this follow-up schedule. Between January 1990 and January 1995, the authors studied all patients with primary laryngeal squamous cell carcinoma who were treated with intention to cure. For patients who developed cancer recurrence, all routine and extra visits were documented. Reported symptoms and physical evidence of tumor were mapped. RESULTS: The patients complied with the follow-up protocol closely. In only 2% of all routine visits an asymptomatic cancer recurrence was found. There was no difference in survival and tumor mortality rates for patients with and without symptoms, despite the difference in whether the therapy applied had the intention to cure. It seemed that patients who developed tumor recurrence after therapy for laryngeal carcinoma received no benefit from screening for cancer recurrence detection. The lack of benefit for cancer detection screening among asymptomatic patients might be explained by unfavorable tumor biology parameters. CONCLUSIONS: The routine follow-up program after treatment for laryngeal carcinoma did not lead to survival benefit for asymptomatic patients with tumor recurrence.

Cause of Death↗

PubMed2004

Estimating life expectancy and related probabilities in screen-detected breast cancer patients with restricted follow-up information.

Issues such as life expectancy after diagnosis, the number of life years gained by early diagnosis through screening, the probability of dying from breast cancer or of dying from other causes during the lead time period or thereafter can be derived from information on complete survival after diagnosis. A method is presented to estimate complete survival and relevant outcomes after diagnosis of screen-detected cancer when the follow-up period is substantially shorter than the maximum follow-up possible. Survival after diagnosis until death from breast cancer is modelled as the sum of the lead time (LT) and the post-lead time (PLT), where both time periods follow exponential distributions and are assumed to be independent. The survival period after diagnosis until death from causes other than breast cancer (X) is assumed to follow a Gompertz distribution. The survival period after diagnosis until death from any cause (Z) is modelled as the minimum of LT+PLT and X. Maximum likelihood methods were then used to estimate all parameters of Z. This procedure for obtaining maximum likelihood estimates of Z does not need the cause of death (breast cancer or other), which is an advantage over most other methods. Especially in older patients, it may be difficult or even impossible to ascertain the true cause of death. The model was applied to data from the long-term breast cancer screening programme in Nijmegen, the Netherlands. Complete survival was estimated on the basis of survival data on 528 screen-detected breast cancer patients, diagnosed in 1975-1997 and with a mean follow-up of 8.9 years. Estimated life expectancy ranged between 22.3 and 9.0 years for patients diagnosed at the age of 50 and 79 years, respectively, that is, 6.1 and 0.7 life years gained by screening. Through early diagnosis and treatment, screen-detected patients diagnosed at the age of 50 years may have reduced their lifetime risk of dying from breast cancer from 79 per cent to 56 per cent; at the age of 79 the reduction of risk is reduced from 23 per cent to 13 per cent.

Aged↗

PubMed2003

Initiation of population-based mammography screening in Dutch municipalities and effect on breast-cancer mortality: a systematic review.

BACKGROUND: More than a decade ago, a mammography screening programme for women aged 50-69 years was initiated in the Netherlands. Our aim was to assess the effect of this programme on breast-cancer mortality rates. METHODS: We examined data for 27948 women who died of breast-cancer aged 55-74 years between 1980 and 1999 (30560 cases until 2001). We grouped individuals into 93 clusters, depending on where they lived, and analysed data by use of national population statistics. We analysed time trends in breast-cancer mortality, adjusting for gradual implementations at municipality level, taking as year 0 the month and year in which screening began in a particular municipality. We used a Poisson regression model to estimate the time at which the trend started to turn. We assessed indirectly whether this turning point was related to initiation of screening or adjuvant systemic therapy in four clusters defined according to when screening was implemented. FINDINGS: Compared with rates in 1986-88, breast-cancer mortality rates in women aged 55-74 years fell significantly in 1997 and subsequent years as predicted, reaching -19.9% in 2001. Mortality rates had been increasing by an annual 0.3% until screening was introduced; thereafter we noted a decline of 1.7% per year (95% CI 2.39-0.96) in women aged 55-74 years and of 1.2% in those aged 45-54 (2.40 to 0.07). The turning point in mortality trends arose at around year 0. Adjuvant systemic therapy is unlikely to be the cause of this turning point, since the mortality rates continued to rise up to 1 year after implementation in municipalities where screening began after 1995. INTERPRETATION: Routine mammography screening can reduce breast-cancer mortality rates in women aged 55-74 years.

Age Distribution↗

PubMed2003

Fear of movement/(re)injury, disability and participation in acute low back pain.

Fear of movement/(re)injury and its associated avoidance behavior have shown to be strongly associated with functional disability in chronic low back pain. In acute low back pain disability, the role of pain-related fear has received little research attention so far. Measures of pain-related fear such as the Tampa Scale for Kinesiophobia (TSK) are increasingly being used in primary care. The aim of the present study was: (1). to further investigate the factor structure of the TSK in a population of acute low back pain (LBP) patients in primary care by means of a confirmatory factor analysis (CFA); (2). to examine the relationship between fear of movement/(re)injury and disability, as well as participation in daily and social life activities in 615 acute LBP patients seen by general practitioners and physical therapists in primary care settings; and (3). to examine whether disability mediates the association between pain-related fear and participation. CFA, and a subsequent explorative factor analysis on the TSK revealed a two-factor model. The factors consisted of items associated with 'harm', and items representing the 'avoidance of activity'. Both constructs were significantly associated with disability and participation. Additionally, and in contrast to what is often observed in chronic pain, disability, and to a lesser degree participation, were also associated with pain intensity. Finally, the association between pain-related fear, pain intensity and participation was indeed mediated by disability. The results suggest that early on in the development of LBP disability, the successful reduction of pain-related fear and disability might foster increased participation in daily and social life activities.

Activities of Daily Living↗