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PubMed2005

Agreement between patient and proxy responses of health-related quality of life after hip fracture.

OBJECTIVES: To examine agreement between patient and proxy respondents on health-related quality of life (HRQL) over time during the 6-month recovery after hip fracture. DESIGN: Prospective longitudinal cohort study. SETTING: A healthcare region serving Edmonton, Alberta, and the surrounding area. PARTICIPANTS: Two hundred forty-five patients aged 65 and older, were treated for hip fracture, and had Mini-Mental State Examination scores greater than 17; 245 family caregivers participated as proxy respondents. MEASUREMENTS: Primary outcome was HRQL (Health Utilities Mark 2 and Mark 3). Interviews were completed within 5 days after surgery and at 1, 3, and 6 months. Agreement was evaluated using intraclass correlation coefficients (ICCs). RESULTS: Agreement was considered moderate to excellent for HRQL. ICC values ranged from 0.50 to 0.85 (P<.001) for physically based observable dimensions of health status and from 0.32 to 0.66 (P<.01) for less-observable dimensions. Agreement improved with time. Time and the number of days between patient and proxy interviews were significant factors in accounting for patient-proxy differences. CONCLUSION: Although proxy and patient responses are not interchangeable, proxy responses provide an option for assessing function and health status in patients who are unable to respond on their own behalf.

Adult↗
PubMed2005

Psychometric evaluation of the multiple sclerosis impact scale (MSIS-29) for proxy use.

BACKGROUND: There may be difficulties in the use of self report measurements in patients with cognitive impairment or serious mood disturbances which interfere with reliable self assessment, as may be the case in multiple sclerosis (MS). In such cases proxies may provide valuable information. However, before using any questionnaires in a proxy sample, the questionnaire should be evaluated for proxy use. OBJECTIVE: To evaluate the psychometric properties of the 29 item Multiple Sclerosis Impact Scale (MSIS-29) when used by proxies of MS patients. METHODS: A sample of 62 partners of MS patients completed the MSIS-29. The data were evaluated for the psychometric criteria of the MSIS-29, including data quality, scaling assumptions, acceptability, reliability, validity, and responsiveness. RESULTS: Psychometric evaluation was satisfactory; data quality was high, and scaling assumptions and acceptability were good. Reliability was high (alpha>0.80). Findings were consistent with results of a psychometric evaluation in a patient sample. CONCLUSIONS: The MSIS-29 can be used reliably in proxies of patients with MS. As a next step the relation between data obtained from patients and proxies needs to be studied, focusing on factors that may affect agreement and discrepancies.

Adult↗
PubMed2001

Reliability of information collected by proxy in family studies of Alzheimer's disease.

The study evaluated the reliability of data obtained from proxy informants. The index subjects in this study were 81 nondemented participants in the Multi-Institutional Research in Alzheimer Genetic Epidemiology (MIRAGE) study. These index subjects and 159 proxy informants, identified by the index subjects, participated in the study. The kappa statistic with multiple raters per subject (for dichotomous variables) and the intraclass correlation coefficient (for continuous variables) were used to measure reliability. Among proxy respondents who provided answers, there was excellent agreement between proxy responses and the responses of the index subjects (0.7 < or = kappa < or =0.9), with the exception of questions about head injury (kappa = 0.4). A large proportion (>90%) of the proxy informants in this study were able to provide information on most items. Higher nonresponse rates (as high as 30%) were observed for medication history and women's health questions. This study supports the reliability of proxy responses for most categories of questions that are elicited in typical epidemiological studies, including the MIRAGE study.

Aged↗
PubMed2004

Agreement between patient and proxy assessments of health-related quality of life after stroke using the EQ-5D and Health Utilities Index.

BACKGROUND AND PURPOSE: Proxy informants can provide information on patients who are limited in ability to self-assess health-related quality of life (HRQL) after stroke. One alternative is to exclude assessments of such patients and attenuate generalizability. The purpose of this study was to examine patient-proxy agreement on the domains and summary scores of the EQ-5D and Health Utilities Index Mark 3 (HUI3) after stroke. METHODS: An observational longitudinal cohort of 124 patients hospitalized after ischemic stroke and their family caregivers completed the HRQL measures at baseline and were followed up for 6 months. Patient and proxy agreement was assessed by use of weighted kappa or the intraclass correlation coefficient (ICC). RESULTS: At baseline, the more observable domains of HRQL demonstrated greater agreement than the more subjective components. Cross-sectional point estimates of agreement were generally acceptable (ICC >0.70) for the EQ-5D Index and HUI3 summary scores when assessed >or=1 month after baseline. Agreement between change scores was generally poor to fair (ICC <0.60), but systematic bias was not observed for the indirect preference-based summary scores between baseline and 6 months. CONCLUSIONS: Results suggest that proxy assessments obtained 6 months after stroke are more reliable than those obtained within 2 to 3 weeks after stroke. Although proxy-assessed change scores for indirect preference-based summary scores of the EQ-5D and HUI3 provided suboptimal agreement with patient assessment, limited systematic bias may support their consideration as alternatives to missing data or statistical imputation. Further research into the validity and reliability of proxy assessments is suggested.

Aged↗
PubMed2000

Hypoxia induces the expression of a 43-kDa protein (PROXY-1) in normal and malignant cells.

This study was designed to determine the expression of cellular factors that may participate in phenotypic changes that occur under conditions of hypoxia. Using the RT-PCR differential display method, we isolated a cDNA fragment corresponding to a gene whose expression was induced in trophoblast and breast carcinoma cells cultured under 1 or 2% oxygen vs 4% oxygen or higher. This gene encodes a 43-kDa protein initially identified in homocysteine-treated endothelial cells and later shown to be upregulated in various human and mouse cell types (termed RTP, Drg1, Cap43, rit42, Ndr1). Herein we refer to this gene product as PROXY-1, for Protein Regulated by OXYgen-1. Elevated mRNA and protein levels were first observed in cells cultured in 1% oxygen for 8 h. Although PROXY-1 mRNA levels returned to near-control values within 2 h of reexposure to 20% oxygen, protein levels remained high 72 h after reexposure to 20% oxygen. Treatment of cells with hypoxia mimics such as cobalt or iron chelators also increased PROXY-1 expression. Moreover, presence of 30% carbon monoxide in the hypoxic atmosphere abrogated the upregulation of PROXY-1 expression. These findings suggest that hypoxia upregulates PROXY-1 levels through a heme protein-dependent pathway and that assessment of PROXY-1 expression may be of potential use in evaluating tissue hypoxia.

Animals↗
PubMed1996

Proxy response patterns among the aged: effects on estimates of health status and medical care utilization from the 1982-1984 long-term care surveys.

We examined the use of proxies in samples of persons aged 65 years and over from the 1982 and 1984 National Long-Term Care Surveys (NLTCS). The NLTCS are designed to describe the Medicare-enrolled elderly population, their health and functioning, hospital, home health, and institutional use. The NLTCS, being longitudinal, allows trends in functional and health status to be examined as well as the changing character of community-based and institutional services used by chronically disabled persons aged 65 years and older. In analyses of proxy responses there was little evidence of differences in accuracy between self- and proxy reports in persons with different health and functional characteristics. The amount and type of proxy reporting did depend on the health and functional characteristics of the sample person. The cognitively impaired, and the frail elderly, had high levels of proxy use as well as small differences in the accuracy of reporting service use and program enrollment. The results are consistent with methodological studies of proxy reporting in health surveys of other populations.

Aged↗
PubMed2002

Ability evaluation by proxy: role of maximal performance and related attributes in social comparison.

Four experiments tested the effects of information about a proxy's related attributes and maximal effort in social comparisons of ability. In Study 1, a proxy's prior performance at maximal effort exerted systematic effects on participants' personal performance predictions for a novel task. When information about the proxy's effort was ambiguous (Study 2). information about related attribute similarity was used in the formulation of performance predictions. In Studies 3 and 4, 2-way interaction terms revealed that participants used related attribute information in generating performance predictions when the proxy's maximum effort was unknown. However, related attribute information was disregarded when proxy's maximum effort was unambiguous. Results were consistent with the proxy comparison model of ability self-evaluation (L. Wheeler, R. Martin, & J. Suls, 1997).

Achievement↗
PubMed1986

Informed consent by proxy. An issue in research with elderly patients.

The need for clinical study of patients in nursing homes is growing as this population grows; yet many of these patients are mentally incompetent to give informed consent for such research, and the decision must therefore be left to family members or other proxies. We studied the decisions by the proxies for 168 patients in nursing homes about whether to permit the patients' participation in a study involving minimal risk. The proxies were family members in all but one case, and 78 of 168 (46 percent) refused consent. Refusal was significantly associated (P less than 0.001) with the views that research should not be done in nursing homes, that the study would disturb the patient, that the patient, if able, would refuse to participate in the study, and that the proxy would refuse to participate in such a study if asked. Of the 55 proxies who believed that the patient would refuse consent, however, 17 (31 percent) gave consent, in apparent opposition to the patient's wishes. We conclude that refusal by family members to allow incompetent elderly patients to participate in studies may be an important obstacle to research among the elderly. Both the selection of proxies and the bases for their decisions require further study and definition.

Aged↗
PubMed2001

Comparison of older adult subject and proxy responses on the SF-36 health-related quality of life instrument.

Studies of older adults' health status and health-related quality of life (HRQoL) often rely on proxy responses when subjects have problems that affect their ability to respond. With the increased interest in outcomes research in health care, it is important to examine proxy reliability on HRQoL instruments. This study compares 32 pairs of subject-andproxy responses on the eight subscales and two summary scales of the Short Form 36 (SF-36). Subjects and their proxies, recruited from senior centers and residential facilities, were interviewed face-to-face within a seven-day period. Subjects were 60 years of age or older and had passed a brief cognitive screen, and proxies were geographically proximate and had seen the subject during the past week. Results showed that although moderate intra-class correlations were found on six of the eight measures, an item-level kappa statistic indicated poor to fair agreement on all subscales except items of Physical Functioning and Role Physical. Moreover, paired t-tests revealed proxy mean scores that were significantly lower on the Physical Functioning, Vitality, and Mental Health subscales. Given the mixed findings, until further research is done, researchers and clinicians should exercise caution when using proxy responses for older adults with the SF-36.

Activities of Daily Living↗
PubMed1997

Effect of proxy-reported smoking status on population estimates of smoking prevalence.

The use of proxy respondents in surveys designed to provide population estimates of smoking prevalence offers an inexpensive way to obtain these data. The accuracy of this information is examined in analyzing data from tobacco use surveys of adults conducted in 22 North American communities as part of the National Cancer Institute's Community Intervention Trial for Smoking Cessation. Proxy-reported smoking status was obtained in a cross-sectional telephone survey conducted from August 1993 to January 1994 (n = 99,682). Self-reported smoking status was obtained from an in-depth interview of a sample of the respondents aged 25-64 years enumerated from the telephone survey (n = 31,417). Discrepancy rates were calculated by comparing the proxy-reported and self-reported smoking statuses of a given individual (n = 10,226). In both surveys, respondents were categorized as current smokers (those who currently smoke and have smoked at least 100 cigarettes in their lifetime), recent quitters (< or = 8 years since cessation), long-term quitters (> 8 years since cessation), and never smokers. The overall discrepancy rate between the self-report and the proxy report was 5.4%. Self-respondents who were black, Hispanic, Asian, recent quitters, or aged 25-34 years were more likely to have inconsistent proxy reports. The authors estimate that the screener interview underestimated the true smoking prevalence by 0.1% when they corrected for smoking status discrepancies. These results confirm that proxy-reported smoking status is an accurate and effective means to monitor populationwide smoking prevalence of adults.

Adult↗
PubMed2000

Reliability of proxy-reported and self-reported household appliance use.

Exposure assessment presents a major challenge for studies evaluating the association between household exposure to electric and magnetic fields and adverse health outcomes, especially the reliance on proxy respondents when study subjects themselves have died. We evaluated the reliability of proxy- and self-reported household appliance exposure. We recruited 92 healthy couples through either random-digit dialing or newspaper advertisements. Trained interviewers administered questionnaires to each member of a couple independently to assess the reliability of proxy-reported household appliance use. Eighty-five couples completed a second interview 2 months later to assess the reliability of self-reported appliance use. Reliability of proxy-reported appliance exposure was good when we inquired about having any exposure to each of the eight indicator appliances during the past year (range of kappa coefficients = 0.63-0.85; median = 0.76) but was lower with increased time to recall or increased detail. Reliability of self respondents reporting 2 months apart was excellent (range of kappa coefficients = 0.75-0.94; median = 0.87) for having any exposure to the eight indicator appliances during the past year, but reliability was again lower with increased detail. When we used self reports at the first interview as the standard, little systematic over- or underreporting occurred for proxy respondents or for self respondents reporting 2 months later. Because this study did not include cases of specific disease, these findings of no systematic differences in reporting do not refer to case or control status. In summary, reliability of self respondents' reports of appliance use is very good for recent time periods and good for broad aspects of exposure in distant time periods. Proxy respondents can provide information regarding broad aspects of appliance exposure in the past year, but detailed aspects of exposure or exposure in more distant time periods is not reliable.

Adult↗
PubMed1991

Investigating the proxy effect and the saliency principle in household based postal questionnaires.

STUDY OBJECTIVE: The aim was to investigate two possible sources of bias inherent in using a household based postal questionnaire, the "proxy effect", inaccurate reporting about characteristics of others, and the "saliency principle", reporting of only the most salient features. This is of importance in surveys concerned with screening the population to identify individuals with certain characteristics, and so possibly relying on one member of the household to reply on behalf of all others. DESIGN AND SETTING: A two stage survey of disablement in the population was undertaken. A first phase postal questionnaire was sent to 25,168 households in Calderdale, West Yorkshire, England, to ascertain the prevalence of physical disability and of troubles with the joints. The second phase comprised in depth interviews with a sample of individuals identified in the first phase as being disabled. RESPONDENTS: A total of 21,889 postal questionnaires were returned (87%) representing households containing 42,826 people aged 16 years and over. A disproportionately stratified random sample of 950 respondents reporting disability was taken in the second phase. Of these 891 were still available, and 838 (94%) were interviewed. MEASUREMENTS AND MAIN RESULTS: The postal questionnaire found that almost 29% of those who lived "alone" (without another adult) reported some level of disability, compared to only 10% of those who lived with others. The difference remained significant after standardisation. This apparent underreporting or "proxy effect" was present for reporting about disability overall, but not for severe disability (dependence on help of others), which suggests the operation of the "saliency principle". Reporting on joint troubles appeared to be affected by the proxy effect both for any joint problems, and when more than five joints were affected. Analysis of a small set of postal questionnaires from respondents who reported joint problems only at interview and where we could identify who had completed the postal questionnaire supports the hypothesis of a proxy effect; two thirds of the original postal questionnaires had been completed by a proxy. The results were further complicated by an interaction between reporting of disability and joint troubles: the greater the level of disability, the less likely the reporting of joint troubles. CONCLUSIONS: The findings have general implications for studies involving postal household screening questionnaires, and raises additional concerns about those that are multitopic in content. In surveys of symptoms and minor disability, a proxy effect is likely to be operative. This effect is not apparent for obvious and long standing problems such as dependence on others for help. However the interaction between the reporting of disability and joint symptoms carries important implications for the development of multitopic postal screening questionnaires.

Adolescent↗
PubMed2005

Proxy completion of EQ-5D in patients with dementia.

There are measurement difficulties associated with the assessment of health-related quality of life (HRQL) in older people with dementia. The use of proxies is a commonly employed approach to overcome such problems. The research reported in this paper sought to identify, specifically for the EuroQol EQ-5D HRQL instrument, whether construct validity is greater for 'family caregivers' or 'clinicians' as two alternative sources of proxy information for patients with a diagnosis of dementia. This involved the exploration of the strength of the associations between clinical measures of illness severity and EQ-5D data. The data appear to reveal a pattern suggesting that the viewpoint of the proxy (i.e., clinician or family caregiver) is important. The findings suggest that the data provided by clinicians (when compared to data from carers) had higher construct validity for the more observable dimensions of the EQ-5D instrument (i.e., 'mobility' and 'self-care'). Conversely, the data from family carers had higher construct validity for the less observable dimensions (i.e., 'usual activities' and 'anxiety/depression'). Previous research on proxy provision of HRQL data has tended to focus on trying to identify a single proxy. The results of this study suggest that using carefully matched sets of measures and assessment perspectives may produce more valid EQ-5D health state descriptions.

Activities of Daily Living↗
PubMed2005

Munchausen by proxy: a case, chart series, and literature review of older victims.

UNLABELLED: The history of an older child victim of Munchausen by proxy (MBP) is described. He was referred for evaluation after repeated sinus surgeries for recurrent sinus infections believed to be related to a falsified history of an immunodeficiency. The perpetrator was the mother of this 14-year-old victim, consistent with the majority of such cases. This case prompted a review of cases of MBP in older children reported in our hospital as well as a literature search for other cases in older children. METHODS: This study was a chart review of children over 6 years of age who had been evaluated by social services at the Children's Hospital at the Cleveland Clinic and reported as cases of Munchausen by proxy to Child Protective Services between January 2001 and June 2003. Also, an OVID, Psychline, and Pubmed literature review of published cases of Munchausen by proxy were identified, and cases occurring in the older child were selected for review. RESULTS: Older children who are the victims of Munchausen by proxy may have an induced illness, but falsified reports of symptoms and medical history to coerce the child to undergo medical procedures may be more common. Collusion of the victim with the perpetrator may also become a factor as the child ages and adopts the deception. Given the complex relationship that exists between the parent and child, it is difficult to predict whether the victim either will assist the caregiver in maintaining the factitious illness or be able to recognize the falsification. CONCLUSIONS: Older children who are the victims of Munchausen by proxy may fear consequences of revealing the factitious illness. Physicians must consider the possibility of this diagnosis whenever there are discrepancies in a child's illness that makes a factitious illness a consideration.

Adolescent↗
PubMed2005

Correspondence between proxy and self-reports on smoking in a full family study.

OBJECTIVES: The present study investigated the reliability of proxy reports obtained from family members with self-reports on adolescent and parental lifetime and current smoking status. METHODS: Data were assessed from 416 families, consisting of both biological parents and two adolescent siblings aged 13-17 years. These families were assessed at baseline and 1 year later. Sensitivity, specificity, positive predictive value and negative predictive value were calculated to test whether proxy reports corresponded with self-reports. RESULTS: Mothers scored higher than fathers on most measures on lifetime and current smoking status of both children. The sensitivity was low for parental reports, but moderate to high for children's reports. Specificity and positive predictive value were high in all proxy reports. The negative predictive value was moderate (parents as proxy reporters) to low (children as proxy reporters) on lifetime smoking, but high on current smoking. CONCLUSIONS: Adolescents, aged 13-17 years, can be used as a reliable source to assess the smoking status of their mothers and fathers. Parents, however, appeared to accurately identify the smoking status of their adolescent children less reliably.

Adolescent↗
PubMed2001

The validity of proxy-based data in suicide research: a study of patients 50 years of age and older who attempted suicide. II. Life events, social support and suicidal behavior.

OBJECTIVE: To investigate the validity of proxy respondent reports of stressful life events, social support and suicidal behavior among individuals who attempted suicide. METHOD: Subjects were 80 psychiatric in-patients admitted following a suicide attempt. Data based on structured interviews with proxy respondents were compared with data based on interviews with subjects (gold standard). RESULTS: Specificity was higher than sensitivity across life event categories, and agreement was substantial for public and observable events (e.g. parent's death) but lower for more ambiguous events. Proxies were good judges of subject reports of frequency of social interaction but not perceived emotional support. Proxies were good judges of past history of suicide attempts and level of suicidal intent. CONCLUSION: Results support proxy-based data on suicidal behavior and certain aspects of social support and stressful life events in research of suicidal behavior in this age group, with potential implications for interpreting postmortem research of completed suicide.

Aged↗
PubMed2005

Are family members suitable proxies for transitional care unit residents when collecting satisfaction information?

OBJECTIVE: To examine the agreement and association of elders' responses with family member proxy responses using the same, previously validated satisfaction instrument on both groups of respondents. METHODS: Satisfaction data came from transitional care unit residents and family members (N = 462 paired responses) from one facility and were collected between 1999 and 2000. The satisfaction questionnaire consisted of 17 items evaluating the art of care, technical quality, efficacy, amenities of the care environment, and global satisfaction. Bias indexes and intraclass correlation coefficients were used to examine the satisfaction scores. RESULTS: In general, proxy satisfaction ratings were higher than ratings of residents. The results also show that proxy ratings varied less from resident ratings for the amenity items, which were considered the most concrete items. Proxy ratings were much higher for the art of care and efficacy domain items, which were considered the least concrete items. CONCLUSION: The results of this investigation show that proxy ratings do not necessarily substitute for resident ratings.

Aftercare↗
PubMedDate not supplied

Evaluating quality of life in children with cancer using children's self-reports and parent-proxy reports.

BACKGROUND: Assessment of quality of life (QOL) of children is complex due to the developmental differences in understanding the content being measured. The validity of parent-proxy reports versus children's self-reports remains to be clarified. OBJECTIVES: To examine the agreement on QOL measures between children's self-reports and parent-proxy reports at different points in time, including at baseline and at 6-month follow up, as well as the change in scores between 6-month follow up and baseline. METHOD: A longitudinal study of QOL assessment of children with cancer for parents and children was conducted. At baseline assessment, 126 children with cancer and at least one of their parents participated (n = 252). Forty boys, 25 girls, and their parents (n = 130) completed the 6-month follow up assessment. RESULTS: Parents tended to report better QOL than did the children at both baseline and 6-month follow up assessments in both the on- and off-treatment groups. Agreement on QOL measure between children and parent proxies varied as a result of the following factors: treatment status (on and off treatment), time (at baseline vs. at 6-month follow up), and changes in score between the time of the baseline assessment and the 6-month follow up. The effects of time, age, gender, and severity of illness had different degrees of significance as predictors on various subscales. DISCUSSION: The predictors of agreement between patients' reports and parent-proxy reports, including the passage of time (from baseline to 6-month follow up), gender, age, and illness severity, have not been conclusively determined. Further studies are needed to examine patient-proxy agreement during a longer follow up period at more than two points in time and using the same patients through the stages of confirmation of diagnosis, acceptance of diagnosis, treatment, and after treatment.

Adolescent↗