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PubMed2004

Assessment of analysis-of-variance-based methods to quantify the random variations of observers in medical imaging measurements: guidelines to the investigator.

The random variations of observers in medical imaging measurements negatively affect the outcome of cancer treatment, and should be taken into account during treatment by the application of safety margins that are derived from estimates of the random variations. Analysis-of-variance- (ANOVA-) based methods are the most preferable techniques to assess the true individual random variations of observers, but the number of observers and the number of cases must be taken into account to achieve meaningful results. Our aim in this study is twofold. First, to evaluate three representative ANOVA-based methods for typical numbers of observers and typical numbers of cases. Second, to establish guidelines to the investigator to determine which method, how many observers, and which number of cases are required to obtain the a priori chosen performance. The ANOVA-based methods evaluated in this study are an established technique (pairwise differences method: PWD), a new approach providing additional statistics (residuals method: RES), and a generic technique that uses restricted maximum likelihood (REML) estimation. Monte Carlo simulations were performed to assess the performance of the ANOVA-based methods, which is expressed by their accuracy (closeness of the estimates to the truth), their precision (standard error of the estimates), and the reliability of their statistical test for the significance of a difference in the random variation of an observer between two groups of cases. The highest accuracy is achieved using REML estimation, but for datasets of at least 50 cases or arrangements with 6 or more observers, the differences between the methods are negligible, with deviations from the truth well below +/-3%. For datasets up to 100 cases, it is most beneficial to increase the number of cases to improve the precision of the estimated random variations, whereas for datasets over 100 cases, an improvement in precision is most efficiently achieved by increasing the number of observers. For datasets of at least 50 cases, the standard error ranges between 30% or less with 3 observers down to 10% or less with 8 observers, and the differences in precision between the methods are negligible. The F test (PWD) is very anticonservative and should not be used, while the t test (RES) is reliable for datasets of at least 2 x 50 cases evaluated by 4 or more observers. The likelihood-ratio-test (REML estimation) consistently indicates the significance of a difference in the random variation of an observer between two groups of cases, regardless of the number of cases, and regardless of the number of observers. If a statistical package to perform REML estimation is available, and the investigator feels confident using it, this is the preferred method for studies that involve less than 50 cases evaluated by less than 6 observers. Otherwise, the RES method is an excellent alternative, because of its straightforward implementation, its completeness with respect to the provided statistics, and its overall sufficient accuracy, precision, and reliability of the provided statistical test. If neither the RES method nor REML estimation can provide sufficient performance, either more observers or more cases must be included.

Algorithms↗

PubMed2002

Radiosurgery for residual or recurrent nonfunctioning pituitary adenoma.

OBJECT: Nonfunctioning pituitary adenomas comprise approximately 30% of all pituitary tumors. The purpose of this retrospective study is to evaluate the efficacy and role of gamma knife radiosurgery (GKS) in the management of residual or recurrent nonfunctioning pituitary adenomas. METHODS: A review was conducted of the data obtained in 42 patients who underwent adjuvant GKS at the University of Pittsburgh between 1987 and 2001. Prior treatments included transsphenoidal resection, craniotomy and resection, or conventional radiotherapy. Endocrinological, ophthalmological, and radiological responses were evaluated. The duration of follow-up review varied from 6 to 102 months (mean 31.2 months). Fifteen patients were observed for more than 40 months. The mean radiation dose to the tumor margin was 16 Gy. Conformal radiosurgery planning was used to restrict the dose to the optic nerve and chiasm. Tumor control after GKS was achieved in 100% of patients with microadenomas and 97% of patients with macroadenomas. Gamma knife radiosurgery was equally effective in controlling adenomas with cavernous sinus invasion and suprasellar extension. No patient developed a new endocrinological deficiency following GKS. One patient's tumor enlarged with an associated decline in visual function. Another patient experienced a deterioration of visual fields despite a decrease in tumor size. CONCLUSIONS: Gamma knife radiosurgery can achieve tumor control in virtually all residual or recurrent nonfunctioning pituitary adenomas. Dose sparing facilitates tumor management even when the adenoma is close to the optic apparatus or invades the cavernous sinus.

Adenoma↗

PubMed2005

Cyclic time course of motor excitability modulation during the observation of a cyclic hand movement.

The observation of a sinusoidal flexion-extension of the wrist was utilized to determine the continuous time course and phase relation between observed movement and its effects on the observer's motor pathways. While observing movements performed by others, the observers' cortical motor areas and spinal circuits were activated, reflecting the specific temporal and muscular pattern of the actual movement (motor resonance). H-reflexes and motor-evoked potentials (MEPs) were elicited, respectively, by electrical stimulation of the median nerve and magnetic stimulation of the appropriate cortical area, in the right forearm muscle Flexor Carpi Radialis (FCR) of subjects who were observing a 1-Hz cyclic oscillation of the right prone hand executed by a different person. Observation elicited a parallel cyclic excitability modulation of the observer's H-reflex and MEP responses with identical period as the observed movement. Modulation was phase advanced, as is muscle activation with respect to the real movement. The same results were obtained when the observed hand oscillation was executed with different frequency (1.6 Hz) and when the hands of mover and observer were supine. No motor resonance was elicited by observing the oscillation of a metal platform. The excitability modulation of MEPs simultaneously monitored in both antagonists of the observer's forearm (FCR and Extensor Carpi Radialis, ECR) was in almost perfect phase opposition, reflecting their natural reciprocal activation during the execution of a hand oscillation. These findings suggest that during observation, motor pathways are modulated subliminally reproducing with high temporal fidelity the motor commands needed to execute the observed movement.

Adult↗

PubMed2001

Validity and reliability of observational methods for studying medication administration errors.

The validity and reliability of observational methods for studying medication administration errors (MAEs) were studied. Between January and June 1998, two pharmacists observed consecutive drug administration rounds by nurses on two wards in a U.K. hospital and recorded all MAEs identified. The observers intervened in cases of potentially harmful errors. MAE records were audited to determine the percentage of omitted doses for which a corresponding reason was documented for the observation periods and for nonobservation periods. Error rates for each drug administration round were analyzed according to whether they were for the nurse's first, second, third (and so on) observed round. Error rates were calculated before and after the first intervention with nurses for whom an intervention was made. Observer reliability was calculated by comparing the rates of errors identified by the two observers. There was no difference between the observation and nonobservation periods in the percentage of omitted doses for which a reason was documented, and there was no change in the error rate with repeated observations. There was no difference in error rates before and after the first intervention for each nurse. There was also no difference in error detection between the two observers and no change with increasing duration of observation. Observation of nurses during drug administration at a U.K. hospital did not significantly affect the MAE rate; nor did tactful interventions by the observers. Observer reliability was high. Concerns about the validity and reliability of observational methods for identifying MAEs may be unfounded.

Chi-Square Distribution↗

PubMed2005

Inter-observer variability in the delineation of pharyngo-laryngeal tumor, parotid glands and cervical spinal cord: comparison between CT-scan and MRI.

BACKGROUND AND PURPOSE: The goal of this study was to compare the inter-observer variability between CT and MRI for the delineation of pharyngo-laryngeal SCC, parotid glands and spinal cord. PATIENTS AND METHODS: Twenty pharyngo-laryngeal tumors were delineated by five observers on CT and MRI, using consistent delineation guidelines. Spinal cords and parotid glands were also delineated on CT and MRI by three observers. Mean GTVs and coefficients of variation were calculated for each observer and compared using ANOVA and its derived Pearson intra-class coefficient (R). For GTVs, a mismatch analysis (ratio between intersection and union volumes) was also performed. RESULTS: Regarding oropharyngeal GTVs (n=10), no significant difference was observed between observers either with CT (33.9, 31.1, 32, 34 and 34.7 ml, five observers, P=0.47) or with MRI (30.5, 29.4, 30.1 and 31.5 ml, four observers, P=0.59). CVs (13.6 vs 12.9%), (0.98 vs 0.99) and mismatches (0.43 vs 0.42) between CT and MRI did not significantly differ. Regarding laryngeal-hypopharyngeal GTVs (n=10), no significant difference was observed between observers either on CT (18.1, 20.7, 20.9, 19.3 and 21.9 ml, five observers, P=0.29) or on MRI (19.3, 21.5, 20, 22.1 and 21.8 ml, five observers, P=0.16). CVs (20.2 vs 13.8%), (0.94 vs 0.94) and mismatches (0.31 vs 0.41) were comparable. Regarding OARs, a small but significant difference in mean parotid volume was observed between observers (P<0.001) and between modalities (P<0.001) (CT: 34.8, 29.4, and 26.8 ml; MRI: 30.6, 27.9 and 20.4 ml). Similar results were obtained for mean spinal cord volumes (CT: 10.7, 10.6, and 9.5 ml; MRI: 8.7, 8.5 and 8.2 ml; P=0.05).

Carcinoma, Squamous Cell↗

PubMed1999

Suicidal inpatients' perceptions of therapeutic and nontherapeutic aspects of constant observation.

OBJECTIVE: Constant observation is a staff-intensive, costly intervention that entails continuous supervision of suicidal inpatients until they no longer express suicidal intent or behavior. This study explored patients' experiences of constant observation to determine whether they derived any therapeutic benefits beyond the intended protective benefit. METHODS: A qualitative research approach was used in which 20 suicidal psychiatric inpatients who had experienced constant observation within the past two weeks were interviewed by researchers not involved in the observation procedure. Thirteen hospital staff members and seven minimally trained lay workers or sitters provided constant observation. RESULTS: Thirteen of the 20 participants emphatically expressed positive feelings toward the observers, particularly when they perceived them as friendly and willing to help. Therapeutic benefits other than protection were largely related to observers' attitudes and behaviors. Patients reported that their dysphoria, anxiety, and suicidal thoughts were decreased by observers who were optimistic, who acknowledged the patient as a human being, who provided distraction with activities and conversation, and who gave emotional support. Nontherapeutic aspects described by participants were observers' lack of empathy, lack of acknowledgment, and failure to provide information about constant observation, as well as a lack of privacy and a feeling of confinement. CONCLUSIONS: The findings support the conclusion that constant observation is not just a protective intervention but one that has therapeutic potential. It can be enhanced if observers engage inpatients in actively supportive interventions. However, observers' perceived attitudes and behaviors can cause patients distress, which reaffirms the need for careful supervision of observers.

Adult↗

PubMed1992

Measurements of tooth length in panoramic radiographs. 2: Observer performance.

Observer performance in tooth-length measurements in panoramic radiography has been examined. Sixty-four teeth, evenly distributed between maxillary first molars, second premolars and mandibular first and second premolars, were fixed in plastic moulds. Each cast was radiographed with an Orthopantomograph, twice with steel balls indicating the cusps and apices of the teeth and once without them. One observer measured the radiographic tooth length twice in both radiographs with indicators in order to estimate the true radiographic tooth length and the repositioning error, and twice in the radiographs without indicators. Seven other observers measured the tooth length on the radiographs without indicators, twice applying their own criteria and twice using defined criteria. The accuracy of the tooth-length measurements was calculated by comparing the true radiographic tooth length with the measurements of the seven observers. The intra-observer variation was defined as the difference between two measurements on the same radiograph. The accuracy and the precision of the tooth-length measurements were highly influenced by the observer performance. The mean radiographic tooth length of the seven observers was closer to the true radiographic tooth length when the observers applied the defined criteria. The inter- and intra-observer variation was higher for the measurements of the maxillary teeth (0.3-1.9 mm) compared with the mandibular teeth (0.3-0.9 mm) for most observers. The highest intra-observer variation was found for the palatal root of the maxillary first molar. The intra-observer variation of four observers decreased somewhat when the defined criteria were used; for the other three observers, however, the variation increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMedDate not supplied

Physician in-field observation of prehospital advanced life support personnel: a statewide evaluation.

STUDY HYPOTHESIS: Direct physician observation of advanced life support (ALS) personnel is rare in a demographically diverse state. STUDY POPULATION: Twenty ALS agencies from throughout Arizona. METHODS: A board-certified emergency physician performed on-site interviews with the emergency medical services (EMS) supervisor of each agency to approximate the number of days per year that physicians observe ALS personnel in the field. RESULTS: Only 11 agencies (55%) reported that physicians ever observed ALS personnel. Among all agencies, an estimated total of 84 observer-days occurred per year. The agencies staffed a total of 86 ALS units, resulting in an estimated 0.98 observer-days/unit/year (84/86). On the average, it took 3.4 ALS personnel to staff a given unit over time and the probability that an ALS provider would be on a unit on any given day was 0.29 (1/3.4). The probability of a given provider being observed during one year was approximately 0.29 (0.98 x 0.29). Thus, on the average, an ALS provider would be observed by a physician approximately once every 3.5 years (1/0.29). Among urban agencies, the "average" ALS provider would be observed once every 2.9 years. This compared to a likelihood of in-field observation of only once every 6.7 years for non-urban providers (p = .036). CONCLUSIONS: The skills of ALS providers in Arizona are observed by a physician in the field very infrequently. Although an uncommon occurrence in urban agencies, observation of non-urban ALS personnel occurs even less frequently. In addition, nearly one-half of the agencies surveyed never had a physician-observer. Although a variety of skills evaluation methods exist, it remains unclear whether any method is as useful as direct observation. Future investigations are needed to evaluate whether in-field physician observation impacts skills, patient care, or outcome in EMS systems.

Arizona↗

PubMed1992

Effects of the model's skill level on observational motor learning.

Observation of a model prior to physical practice often facilitates the acquisition of motor skills. The majority of research studies on observational motor learning has used a skilled model for the demonstration. Recent research, however, suggests that observing an unskilled (learning) model may also be effective. The experiment reported here compared motor skill acquisition following observation of a learning model or a skilled model to the performance of subjects who lacked the benefit of observation. The task was to play a computer tracking game. Subjects were tested in pairs. Observers watched either a skilled or a learning model perform 3 trials. The observers then practiced the game for 3 trials. Observation of another 12 trials was followed by 12 more practice trials. Substantial observational learning was found, as both groups of observers performed better than the learning models after both the 3 initial trials of observation and after 12 more observation trials. However, there were no differences due to observing the skilled or the learning model. These findings are discussed in relation to theoretical issues of observational learning.

Analysis of Variance↗

PubMed2005

Observation of action and autonomic nervous system responses.

Observing somebody performing an action has been shown to elicit neuronal activity in the premotor cortex. This paper investigated physiological effect of observing an effortful action at the peripheral level. As Autonomic Nervous System responses reflect central nervous system processes such as movement planning and programming, it was expected that observing an action would elicit a pattern of ANS responses matching those recorded during actual movement. 12 male subjects, ages 23 to 28 years (M = 25.5, SD = 1.9), were selected as they were experienced in weight lifting. They were asked to observe a squat movement followed by returning to the upright position under 3 different conditions: (i) observation of actual movement performed by somebody else, (ii) observation of a video of the subject himself (first-person video), and (iii) observation of a video of somebody else performing the same movement (third-person video). Moreover, each movement was observed when performed at 50% and 90% of each participant's personal best mark (% of the highest weight which could be lifted). Three ANS parameters were continuously recorded: skin resistance, temperature and heart rate. ANS responses varied as a function of movement intensity: autonomic responses recorded during movement observation at 90% were significantly higher and longer than those recorded during movement observation at 50%. Thus, autonomic responses were linked to the amount of observed effort. Conversely, no difference was found among the three conditions of observation. ANS responses from observation of actual movement were shown to resemble those recorded under the two conditions of video observation.

Adult↗

PubMed1996

Inter-observer reliability of the Spondylitis Functional Index Instrument for assessing spondylarthropathies.

OBJECTIVE: To study the Spondylitis Functional Index (SFI) by having two physical therapists observe patients with spondylitis perform various tasks listed on the instrument. The physical therapists' observations were compared with each other and with the self-reported abilities of the patients. METHODS: Subjects (n = 30) were recruited from a cross-section of patients participating in a prospective randomized, multicenter, double-blind, parallel clinical trial of the efficacy of sulfasalazine on ankylosing spondylitis (n = 13), psoriatic arthritis (n = 13), and Reiter's syndrome (n = 4) conducted at the Veterans Affairs Medical Center in Salt Lake City. Percents of agreement and Cohen's kappa analysis were used to assess the reliability of the observations of the therapists and patients. RESULTS: The overall percent of agreement between the observers on the SFI was 93%. The overall percent of agreement between observer 1 and patients on the SFI was 66% and between observer 2 and patients was 67%. The overall inter-observer reliability measured by the Pearson coefficient was 0.91 and by Cohen's kappa was 0.86. Between observer 1 and the patients the Pearson was r = 0.53 and kappa = 0.39. For observer 2 the Pearson was r = 0.52 and kappa 0.39. CONCLUSIONS: We consider the agreement and reliability between observers to be high. The agreement and inter-observer reliability was poor between observers and patients. The SFI, as enhanced for use in this study to assess change in functional ability of patients with spondylitis, demonstrated high reliability when used by trained observers.

Activities of Daily Living↗

PubMed2003

The use and effectiveness of an emergency department observation unit for elderly patients.

STUDY OBJECTIVE: Emergency department observation units are cost-effective alternatives to hospital admission for selected patients. However, the use and effectiveness of these units in the elderly population is unclear. We sought to describe the use of an ED observation unit by elderly patients (>or=65 years), to determine whether the ED observation unit is effective for them in terms of ED observation unit length of stay and hospital admission rates, and to compare efficacy and return visit rates between younger and older patients. METHODS: This is a retrospective observational cohort study of consecutive adult patients sent to an ED observation unit from 1996 to 2000 at a high-volume tertiary care suburban teaching hospital. ED observation unit length of stay of less than 18 hours and admittance rates of less than 30% were used as indicators of efficacy. Diagnosis, length of stay, hospital admission rates, and 30-day return visit rates were compared between younger and older patients. RESULTS: Twenty-two thousand five hundred and thirty adult patients were observed, with 37.2% older than 65 years of age. The most common diagnoses in elderly patients were chest pain (24.0%), dehydration (11.7%), syncope (6.5%), back pain (4.6%), and chronic obstructive pulmonary disease (3.8%). Length of stay in the ED observation unit was longer for the elderly than younger patients but still averaged less than 18 hours (15.8 hours [95% confidence interval (CI) 15.7 to 16.0] versus 14.4 hours [95% CI 14.3 to 14.5], respectively). Elderly patients were more likely to be admitted from the ED observation unit than younger patients (26.1% versus 18.5%); however, their overall admission rate remained less than 30%. Compared with younger patients, the odds ratios for inpatient admission of elderly patients was highest for back pain (2.10; 95% CI 1.62 to 2.73), pyelonephritis (1.78; 95% CI 1.16 to 2.71), and chest pain (1.65; 95% CI 1.44 to 1.89). Thirty-day related return visit rates between age groups were similar (9.4% versus 7.6%). CONCLUSION: Elderly ED observation unit patients had ED observation unit lengths of stay and hospital admission rates that were effective for an ED observation unit setting and ED return visits rates that were comparable with those of younger patients.

Adult↗

PubMed2006

The trained observer better predicts daytime ABPM diastolic blood pressure in hypertensive patients than does an automated (Omron) device.

OBJECTIVES: Accurate blood pressure measurement is critical to successful clinical trials. Concerns about observer errors have led to the use of automated oscillometric devices without evidence that their performance is similar to that of trained observers. This study compares blood pressures obtained by trained observers and with an oscillometric device (Omron 705CP) to 24-h ambulatory blood pressure monitoring. METHODS: We performed a post-hoc analysis of 313 untreated hypertensive patients at the end of the washout phase of a Novartis hypertension trial. Patients had three seated trained observer mercury auscultatory blood pressure measurements followed by 24-h ambulatory blood pressure monitoring. The next day, the ambulatory blood pressure monitoring was removed and three seated readings were obtained with an Omron 705CP. Correlations for systolic blood pressure and diastolic blood pressure were obtained between daytime ambulatory blood pressure monitoring (0900 and 2100) and the two office methods. In addition, we investigated the degree of difference of trained observer and Omron measurements from ambulatory blood pressure monitoring. RESULTS: For systolic blood pressure, the correlation with ambulatory blood pressure monitoring of the trained observer was significantly better than with that of the Omron 705CP (0.641 vs. 0.555, P=0.01). For diastolic blood pressure values, even greater disparity between the two office method correlations with ambulatory blood pressure monitoring was observed (trained observer=0.593 vs. Omron=0.319, P<0.0001). Both trained observer and Omron readings were consistently higher than ambulatory blood pressure monitoring for systolic blood pressure (P<0.0001) and diastolic blood pressure (P<0.0001). Omron measurements, however, deviated from ambulatory blood pressure monitoring more than those of the trained observer (P<0.0001 for systolic blood pressure and diastolic blood pressure). CONCLUSIONS: For clinical trials using diastolic blood pressure targets, the Omron 705CP cannot replace the auscultatory blood pressure measurements of a trained observer. For systolic blood pressure, the Omron device and the trained observer had similar correlations with ambulatory blood pressure monitoring; however, both methods gave consistently higher systolic blood pressure values. Further study of oscillometric devices should be conducted before universally replacing auscultatory blood pressure determinations by trained observers in clinical trials.

Adult↗

PubMed1998

Inter- and intra-observer variation in the histopathological reporting of cervical squamous intraepithelial lesions using a modified Bethesda grading system.

OBJECTIVE: 1. To assess inter- and intra-observer variation in the histopathological reporting of cervical colposcopic biopsies using a histologic modification of the cytological Bethesda grading system; 2. to determine the histologic profile of those cases which resulted in diagnostic disagreement. METHODS: Consecutive cervical colposcopic biopsies (n = 125) were assessed independently by six experienced histopathologists. Cases were classified as normal, low grade squamous intraepithelial lesion or high grade squamous intraepithelial lesion. Six months later the process was repeated. The degree of inter and intra-observer variation was assessed by kappa statistics. All cases in which there was less than perfect inter and intra-observer agreement were reviewed by the coordinator of the study. RESULTS: In the first round of the study inter-observer agreement was generally poor, with unweighted and weighted kappa values ranging from 0.15 to 0.58 (average 0.30) and from 0.21 to 0.61 (average 0.36) respectively. In the second round inter-observer agreement was better, with unweighted and weighted kappa values ranging from 0.08 to 0.55 (average 0.33) and from 0.22 to 0.59 (average 0.42). Ten of the 15 pairs of observers achieved fair inter-observer agreement using weighted kappa analysis. The degree of intra-observer agreement was better, unweighted and weighted kappa values ranging from 0.26 to 0.61 (average 0.47) and from 0.34 to 0.62 (average 0.51) respectively. Two of the six participants achieved fair intra-observer agreement and two achieved good intra-observer agreement using weighted kappa analysis. There were marked difficulties in the separation of normal squamous epithelium from low grade squamous intraepithelial lesion and in the separation of low grade from high grade squamous intraepithelial lesions. Histopathological review revealed that many of the difficulties in the separation of normal and low grade squamous intraepithelial lesion were in the distinction between superficial vacuolated cells and true koilocytes. Difficulties also resulted in the separation of basal cell hyperplasia, inflammatory associated changes and immature squamous metaplasia from low grade squamous intraepithelial lesion. Conditions which resulted in difficulty in the separation of low grade and high grade squamous intraepithelial lesions included florid koilocytotic change and immature metaplastic squamous epithelium with atypia. In some cases, there was a full spectrum of diagnoses from normal to high grade squamous intraepithelial lesion. These were largely cases of immature metaplastic squamous epithelium with atypia and of thin or atrophic squamous epithelium with atypia. CONCLUSIONS: Most pairs of observers can achieve fair inter-observer agreement in the reporting of cervical colposcopic biopsies using a modified Bethesda system. Intra-observer agreement is also generally fair to good using this system. It may be that a two tier grading system is more appropriate for the histopathological reporting of these biopsies than the traditional three-tier intraepithelial neoplasia (CIN) system.

Biopsy↗

PubMed2000

Observer variability in optic disc assessment: implications for glaucoma shared care.

Demonstrating that optometrists can make valid and reliable assessments of optic disc features is an important prerequisite for establishing schemes for shared care/co-management. Previous studies have estimated observer variability among experts in the assessment of optic disc cupping, but there has been a paucity of information on observer variability amongst optometrists. This paper describes a study to investigate intra- and inter-observer variability for a range of disc features, as graded by both ophthalmologists and optometrists. Five observers (three optometrists and two ophthalmologists) graded 48 stereo-pairs of optic disc photographs from 48 patients on two separate occasions. Each observer graded the following features: vertical and horizontal C/D ratios, narrowest rim width, the presence/absence of a disc haemorrhage, focal pallor of the neuroretinal rim, peri-papillary atrophy, the steepness of the cup-edge and the presence/absence of the cribriform sign. The average intra- and inter-observer standard deviation (SD) of differences are, respectively, 0.11 and 0.19 for the vertical C/D ratios and 0.10 and 0.18 for the horizontal C/D ratios. For the vertical C/D ratio the average weighted kappa (kappa w) is 0.79 within observers and 0.46 between observers. Percentage agreements for the presence/absence of a disc haemorrhage range from 96 to 100% (average kappa = 0.92) within observers and from 90 to 98% (average kappa = 0.77) between observers. For other disc features, average kappa w values range from 0.67 to 0.71 within observers and from 0.23 to 0.46 between observers. Intra- and inter-observer comparisons (within and between different professionals) across all disc features are comparable for the optometrists and ophthalmologists, thus demonstrating that optometrists can make valid assessments of disc features. The implications for shared care are discussed.

Glaucoma, Open-Angle↗

PubMed1998

Laparoscopic cholecystectomy: day-care versus clinical observation.

OBJECTIVE: To determine the feasibility and desirability of laparoscopic cholecystectomy (LC) in day-care versus LC with clinical observation. SUMMARY BACKGROUND DATA: Laparoscopic cholecystectomy has been performed regularly as outpatient surgery in patients with uncomplicated gallstone disease in the United States, but this has not been generally accepted in Europe. The main objections are the risk of early severe complications (bleeding) or other reasons for readmission, and the argument that patients might feel safer when observed for one night. Quality-of-life differences hitherto have not been investigated. METHODS: Eighty patients (American Society of Anesthesiology [ASA] I/II) with symptomatic gallstones were randomized to receive LC either in day-care or with clinical observation. Complications, (re)admissions, consultations of general practitioners or the day-care center within 4 days after surgery, use of pain medication, quality of life, convalescence period, time off from professional activities, and treatment preference were assessed. The respective costs of day-care and clinical observation were determined. RESULTS: Of the 37 patients assigned to the day-care group who underwent elective surgery, 92% were discharged successfully after an observation period of 5.7+/-0.2 hours. The remainder of the patients in this group were admitted to the hospital and clinically observed for 24 hours. For the 37 patients in the clinical observation group who underwent elective surgery, the observation time after surgery was 31+/-3 hours. Three patients in the day-care group and one patient in the clinical observation group had complications after surgery. None of the patients in either group consulted a general practitioner or the hospital during the first week after surgery. Use of pain medication was comparable in both groups over the first 48 hours after surgery. There were no differences in pain and other quality-of-life indicators between the groups during the 6 weeks of follow-up. Of the patients in the day-care group, 92% preferred day-care to clinical observation. The same percentage of patients in the clinical observation group preferred at least 24 hours of observation to day-care. Costs for the day-care patients were substantially lower (approximately $750/patient) than for the clinical observation patients. CONCLUSION: Effectiveness was equal in both patient groups, and both groups appeared to be satisfied with their treatment. Because no differences were found with respect to the other outcomes, day-care is the preferred treatment in most ASA I and II patients because it is less expensive.

Adult↗

PubMed2003

Long-term socio-economic impact of vestibular schwannoma for patients under observation and after surgery.

This study describes and compares the long-term socio-economic impact for patients diagnosed with a vestibular schwannoma and either operated on or observed. A consecutive sample of patients diagnosed with vestibular schwannoma in Denmark and either operated on (748 patients) or observed by the wait-and-re-scan policy (272 patients) during the period 1976-2000 were studied retrospectively. The consequences of operation/diagnosis (and observation) on vocational status, ability to handle daily chores and some psycho-social aspects were studied by means of a prospective postal questionnaire. Ninety-six per cent of the operated and 83 per cent of the observed patients answered the questionnaire. Overall, 34 per cent of operated patients resumed their daily activities within one to two months, and 76 per cent within four to six months. Patients operated on for a large tumour resumed their daily activities later than patients with a small tumour. Regardless of tumour size, employment was unchanged for the majority of observed and operated patients. The vocational consequences were significantly worse for operated patients with a large tumour, than for observed patients. However, no difference existed between the observed group and operated patients with a tumour below 20 mm in size. A change in vocational status was most frequent for assisting spouses, unskilled manual workers and the self-employed. The majority of both observed and operated patients experienced no change in their ability to handle daily chores. The changed ability of operated patients was worse than that of observed patients. Among various changes in their psycho-social well-being, decrease in social ability was the most frequent complaint in both groups, followed by increased fatigue, decreased concentration, increased irritability, depression and headache, decreased intellect and libido. Regardless of tumour size, the change in social ability, concentration and fatigue was worse for operated patients. Concerning headache, patients operated on for a large tumour were better off than observed patients and patients operated on for a small tumour. There was no difference between the operated and observed groups concerning irritability, intellect and libido. Deterioration of vocational status, ability to handle daily chores and several aspects of psycho-social well-being are reported both by patients operated on and observed for vestibular schwannoma. However, the negative changes were more frequent among the operated patients, although the differences were surprisingly modest, especially when comparing observed patients with patients operated on for a small tumour.

Activities of Daily Living↗

PubMed2001

Human- and model-observer performance in ramp-spectrum noise: effects of regularization and object variability.

We consider detection of a nodule signal profile in noisy images meant to roughly simulate the statistical properties of tomographic image reconstructions in nuclear medicine. The images have two sources of variability arising from quantum noise from the imaging process and anatomical variability in the ensemble of objects being imaged. Both of these sources of variability are simulated by a stationary Gaussian random process. Sample images from this process are generated by filtering white-noise images. Human-observer performance in several signal-known-exactly detection tasks is evaluated through psychophysical studies by using the two-alternative forced-choice method. The tasks considered investigate parameters of the images that influence both the signal profile and pixel-to-pixel correlations in the images. The effect of low-pass filtering is investigated as an approximation to regularization implemented by image-reconstruction algorithms. The relative magnitudes of the quantum and the anatomical variability are investigated as an approximation to the effects of exposure time. Finally, we study the effect of the anatomical correlations in the form of an anatomical slope as an approximation to the effects of different tissue types. Human-observer performance is compared with the performance of a number of model observers computed directly from the ensemble statistics of the images used in the experiments for the purpose of finding predictive models. The model observers investigated include a number of nonprewhitening observers, the Hotelling observer (which is equivalent to the ideal observer for these studies), and six implementations of channelized-Hotelling observers. The human observers demonstrate large effects across the experimental parameters investigated. In the regularization study, performance exhibits a mild peak at intermediate levels of regularization before degrading at higher levels. The exposure-time study shows that human observers are able to detect ever more subtle lesions at increased exposure times. The anatomical slope study shows that human-observer performance degrades as anatomical variability extends into higher spatial frequencies. Of the observers tested, the channelized-Hotelling observers best capture the features of the human data.

Artifacts↗