Utility of proxy versus index respondent information in a population-based case-control study of rapidly fatal cancers

Accuracy of Smoking Status Reporting: Proxy Information in a Rapidly Fatal Cancer Setting

Objective

To assess whether patients and relatives can serve as reliable proxy reporters of other family members’ cigarette-smoking history.

Patients and Methods

Two samples (325 patients, 707 relatives) were identified from the Mayo Clinic Biospecimen Resource for Pancreas Research, enrolled from November, 6, 2000, to March 15, 2018. Smoking-history data, including categorical (ever/never) and quantitative (packs per day and years smoked) smoking measures, were obtained from self-completed questionnaires by patients and relatives. Relative reports were compared with patient reports on self; patient reports were compared with relative reports on self.

Results

Overall, spouses and first-degree relatives (FDRs) were accurate (94.5%) when reporting patient ever smoking; spouse reports were 98.6% sensitive and 97.7% accurate. Accuracy of patient reports was 97.8% for spouse smoking and 85.5% for FDR smoking; accuracy varied by relationship of FDR. When not concordant, patients generally over-reported daily packs smoked by relatives and under-reported years smoked. Within a 25% agreement range, spouse reports about patients’ daily packs smoked was 46.7%, and years smoked was 69.6%, whereas FDRs were 50% and 64.6%, respectively. When not concordant, relatives generally over-reported daily packs smoked by patients, but no consistent pattern was observed of over- or under-reporting years smoked by patients.

Conclusions

Patients and relatives can be reliable proxies for smoking history (ever/never) in their family members, especially spouses. An accurate reporting of smoking status will help physicians to better gauge performance status and family smoking exposures to inform disease management.

Risk factors for suicide among older adults with cancer

OBJECTIVE

To determine whether the increased risk of suicide for individuals with cancer may be explained by functional limitations, lack of social support, or other factors.

METHOD

In this population-based case-control study, interviews of primary informants for suicides in the state of North Carolina were compared to interviews with participants in the Piedmont Health Study of the Elderly to estimate adjusted odds ratios for suicide and self-reported, physician diagnosed cancer, heart attack, stroke, and hip fracture.

RESULTS

Adjusting for all other factors, there was a statistically significant association of suicide and cancer (odds ratio [OR] 2.62, 95% confidence interval [CI] CI 1.84-3.73), but not heart attack, hip fracture, or stroke. The risk of suicide was also elevated for men vs. women (OR 17.15, CI 10.88-27.02), whites vs. blacks (OR 9.70, CI 6.07-15.50), and individuals with stressful life events (OR 2.75, CI 1.97-3.86) or limitations of instrumental (OR 2.93, CI 2.03-4.22) but not physical activities of daily living. Suicide cases were not more likely to be short of breath or poor sleep quality. Suicide was statistically significantly less likely for study participants who were married with spouse living vs. other (OR 0.61, CI 0.43-0.88) or who had one or more indicators of social support (OR 0.27, CI 0.19-0.39).

CONCLUSION

After adjustment for other risk factors, suicide was strongly associated with cancer but not with other disabling, potentially fatal conditions.

Post-diagnosis physical activity and survival after breast cancer diagnosis: the Long Island Breast Cancer Study

Physical activity (PA) is associated with physiological responses thought to beneficially affect survival after breast cancer diagnosis, yet few studies have considered the entire survivorship experience. Effects of post-diagnosis activity on survival were examined in a cohort of 1,423 women diagnosed with in situ or invasive breast cancer in 1996-1997. Subjects were interviewed soon after diagnosis and again after approximately 5 years to assess breast cancer-related factors, including recreational PA before and after diagnosis. Date and cause of death through 2009 were determined from the National Death Index. Adjusted estimates were obtained using proportional hazards regression and a selection model to account for missing data. Survival was improved among women who were highly active after diagnosis (>9.0 MET h/week) compared to inactive women (0 MET h/week) for all-cause [hazard ratio (HR) (95 % credible interval): 0.33 (0.22, 0.48)] and breast cancer-specific mortality [HR: 0.27 (0.15, 0.46)]. The association of PA with overall mortality appeared stronger in the first 2 years after diagnosis [HR: 0.14 (0.03, 0.44)] compared to 2+ years since diagnosis [HR: 0.37 (0.25, 0.55)]. These findings show that post-diagnosis PA is associated with improved survival among women with breast cancer.

Reliability of Family Proxy Data for Studies of Malignant Mesothelioma: Results from the ATSDR Pilot Surveillance

Objective. To evaluate the validity of proxy interviews in obtaining information on persons with rapidly fatal diseases such as malignant mesothelioma (MM). Methods. Persons with MM diagnosed in 2002 through 2005 in New York and New Jersey and 1997–2004 in Wisconsin were eligible for inclusion in the project. Persons with MM and their family member proxy were interviewed using the same questionnaire designed by ATSDR to collect information on potential direct or indirect occupational and environmental exposure to asbestos, genetic, and health related malignancy predisposition, and exposure to tobacco products. Descriptive statistics and the McNemar/Durkalski test were used to analyze 33 matched pairs. Results. The overall study confirmed a generally high ability of proxies to give interviews of comparable quality and completeness when asked dichotomous questions. The reliability of information collected from proxies varied by topic and family relationship. Conclusions. Family proxy interviews, using dichotomous responses, can serve as an acceptable source of information about health and exposure-related risk factors for MM.

Effect of survey instrument on participation in a follow-up study: a randomization study of a mailed questionnaire versus a computer-assisted telephone interview

BACKGROUND

Many epidemiological and public health surveys report increasing difficulty obtaining high participation rates. We conducted a pilot follow-up study to determine whether a mailed or telephone survey would better facilitate data collection in a subset of respondents to an earlier telephone survey conducted as part of the National Birth Defects Prevention Study.

METHODS

We randomly assigned 392 eligible mothers to receive a self-administered, mailed questionnaire (MQ) or a computer-assisted telephone interview (CATI) using similar recruitment protocols. If mothers gave permission to contact the fathers, fathers were recruited to complete the same instrument (MQ or CATI) as mothers.

RESULTS

Mothers contacted for the MQ, within all demographic strata examined, were more likely to participate than those contacted for the CATI (86.6% vs. 70.6%). The median response time for mothers completing the MQ was 17 days, compared to 29 days for mothers completing the CATI. Mothers completing the MQ also required fewer reminder calls or letters to finish participation versus those assigned to the CATI (median 3 versus 6), though they were less likely to give permission to contact the father (75.0% vs. 85.8%). Fathers contacted for the MQ, however, had higher participation compared to fathers contacted for the CATI (85.2% vs. 54.5%). Fathers recruited to the MQ also had a shorter response time (median 17 days) and required fewer reminder calls and letters (median 3 reminders) than those completing the CATI (medians 28 days and 6 reminders).

CONCLUSIONS

We concluded that offering a MQ substantially improved participation rates and reduced recruitment effort compared to a CATI in this study. While a CATI has the advantage of being able to clarify answers to complex questions or eligibility requirements, our experience suggests that a MQ might be a good survey option for some studies.

Postdiagnosis change in bodyweight and survival after breast cancer diagnosis

BACKGROUND

Weight gain after diagnosis is common among women with breast cancer, yet results have been inconsistent among the few studies examining its effects on survival.

METHODS

We examined the effects of weight gain on mortality among a cohort of 1436 women diagnosed with a first primary breast cancer in 1996-1997, on Long Island, NY. Subjects were interviewed soon after diagnosis and again after approximately 5 years. Weight was assessed at each decade of adult life; 1 year before, at, and 1 year after diagnosis; and at the time of follow-up. Mortality through the end of 2005 was assessed using the National Death Index. Proportional hazards regression was used while using a selection model to account for missing data.

RESULTS

Compared with women who maintained their prediagnosis weight (±5%), those who gained more than 10% after diagnosis had worse survival (hazard ratio [HR] = 2.67; [95% credible interval = 1.37-5.05]). The effect was more pronounced during the first 2 years after diagnosis (>5% gain: all-cause mortality in the first 2 years, HR = 5.87 [0.89-47.8] vs. after 2 years, 1.49 [0.85-2.57]); among women overweight before diagnosis (overweight women: all-cause HR = 1.91 [0.91-3.88] vs. ideal-weight women, 1.39 [0.62-3.01]); and for women who had gained at least 3 kg in adulthood before diagnosis (≥3-kg gain before diagnosis: 1.80 [0.99-3.26 vs. <3 kg gain before diagnosis: 1.07 [0.30-3.37].

CONCLUSIONS

These results highlight the importance of weight maintenance for women after breast cancer diagnosis.

Occupational silica exposure and chronic kidney disease

INTRODUCTION

Occupational exposure to silica may be associated with chronic kidney disease (CKD). Most studies have been conducted in occupational cohorts with high levels of exposure but small numbers of cases. We analyzed data from a population-based case-control study of occupational silica exposure and CKD.

METHODS

Cases were hospital patients with newly diagnosed CKD, and community controls were selected using random digit dialing and frequency matched by age, gender, race, and proximity to the hospital. Silica exposure estimates were assigned by industrial hygiene review of lifetime job history data and weighted for certainty and intensity. Conditional logistic regression was used to estimate the odds ratios (ORs) for CKD conditioned on demographic, lifestyle, and clinical variables.

RESULTS

The mean age of participants was 63 years (range 30-83 years); 59% were male and 55% were white. Any silica exposure (compared with none) was associated with a 40% increased risk of CKD [OR = 1.40, 95% confidence interval (CI): 1.04, 1.89] in a multivariable adjusted model. The mean cumulative duration of silica exposure was significantly higher in exposed cases than in exposed controls (33.4 vs. 24.8 years, respectively). Overall, compared with nonexposed participants, the ORs (95% CI) for those below and above the median duration of silica exposure were 1.20 (0.77, 1.86) and 1.76 (1.14, 2.71), respectively.

CONCLUSIONS

We found a positive relationship between occupational silica exposure and CKD. A dose-response trend of increasing CKD risk with increasing duration of silica exposure was observed and was particularly strong among nonwhites.

Maternal occupational pesticide exposure and risk of hypospadias in the National Birth Defects Prevention Study

BACKGROUND

Hypospadias is a common congenital malformation among men in which the urethral opening is ventrally displaced. Pesticide exposure has been suggested as a possible etiologic factor, but previous epidemiologic studies have produced inconsistent results.

METHODS

We used data from the National Birth Defects Prevention Study (NBDPS), a population-based case-control study, to examine maternal occupational exposure to fungicides, insecticides, and herbicides among 647 hypospadias case infants and 1496 unaffected male control infants with estimated delivery dates from October 1997 to December 2002. Periconceptional (1 month before conception through the first trimester of pregnancy) pesticide exposures were assigned by an expert rater, assisted by a job-exposure matrix (JEM), from a job history completed by mothers during a telephone interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with multivariable logistic regression, and adjusted for relevant covariates.

RESULTS

Maternal periconceptional occupational exposure to any pesticides (yes/no) was not associated with an increased risk of hypospadias (OR = 0.78; 95% CI = 0.61-1.01). Maternal occupational periconceptional pesticide exposure type (insecticides, fungicides, and herbicides) and estimated quantity also showed no significantly increased risk of hypospadias and no evidence of a dose-response relationship; however, the estimated pesticide exposure levels in this population were low.

CONCLUSION

Using broad classes of insecticides, herbicides, and fungicides, we found no evidence that low intensity maternal periconceptional occupational pesticide exposure was a risk factor for hypospadias.

Completeness and utility of interview data from proxy respondents in prenatal care research in rural China

In household surveys, the use of data provided by relatives can increase response rates and generalisability of research findings. This study assessed the quality of data from relatives and the impact of the data source on the association between the use of prenatal care and pregnancy outcomes. Data for 3,673 new mothers and 293 proxy respondents were available from a house-hold survey in 2008-2009 in rural China. Analyses were performed using chi-square test, ANOVA, Kruskal-Wallis test, and logistic regression models. Differences in the studied variables were small, but proxy respondents were slightly more likely to have missing data than the new mothers. Differences and missing data were more common for the use of prenatal care and outcome variables (mode of delivery, place of delivery, birth weight, use of postnatal care, and gestational age at birth) than for the background characteristics of the participants. Husbands' reports were closer to the index reports than that of the other proxies. The associations between the exposures and outcomes were mostly similar between the proxy and index respondents. Relatives can be interviewed instead of women to study prenatal care without a substantial negative impact on study results. Studies using proxy respondents should stratify the analysis by type of respondents.

A Bayesian proportional hazards regression model with non-ignorably missing time-varying covariates

Missing covariate data are common in observational studies of time to an event, especially when covariates are repeatedly measured over time. Failure to account for the missing data can lead to bias or loss of efficiency, especially when the data are non-ignorably missing. Previous work has focused on the case of fixed covariates rather than those that are repeatedly measured over the follow-up period, hence, here we present a selection model that allows for proportional hazards regression with time-varying covariates when some covariates may be non-ignorably missing. We develop a fully Bayesian model and obtain posterior estimates of the parameters via the Gibbs sampler in WinBUGS. We illustrate our model with an analysis of post-diagnosis weight change and survival after breast cancer diagnosis in the Long Island Breast Cancer Study Project follow-up study. Our results indicate that post-diagnosis weight gain is associated with lower all-cause and breast cancer-specific survival among women diagnosed with new primary breast cancer. Our sensitivity analysis showed only slight differences between models with different assumptions on the missing data mechanism yet the complete-case analysis yielded markedly different results.

Exposures in painting related occupations and risk of selected cancers: results from a case-control study in Montreal

BACKGROUND

Painters are considered to be at increased risk of lung cancer. The objective was to evaluate risk of several cancers, apart from lung, in painting-related professions. Most previous studies have focused on the job title rather than on exposures incurred.

METHODS

A large population based case-control study was carried out during 1979-1986 in Montreal including several types of cancer and focusing on occupational exposures. Interviews elicited detailed lifetime job histories; those were evaluated by a team of industrial hygienists to assign exposure. The exposure checklist included three paint-related substances: metal coatings, wood varnishes and stains, and wood and gypsum paints. Seven types of cancer were analyzed (numbers interviewed): esophagus (97), stomach (248), colorectal (754), prostate (438), bladder (478), kidney (174) and non-Hodgkin's lymphoma (215). For each cancer type, a pooled control group was constituted from 533 population controls and 533 cancer patients selected from other types of cancer. Odds ratios (ORs) were estimated between each of the paint-related agents and each of the seven cancer types, adjusting for several potential confounders, including smoking.

RESULTS

The job title of "painters" was not associated with risk of any of the cancers under study. Most of the ORs between the three agents and the seven cancers were close to null. However, there was a tendency for ORs to be above 1.0 for subjects who had substantial exposure to metal coatings, with noteworthy associations for cancers of the esophagus (OR = 4.2; 95% CI: 1.1-17.0; n = 4), prostate (OR = 2.7; 95% CI: 1.0-7.7; n = 13), and bladder (OR = 1.7; 95% CI: 0.7-4.4; n = 13).

CONCLUSION

These results are compatible with an absence of risk among painting-related professions; they are also compatible with excess risk of certain cancers, especially among those exposed to metal coatings.

Does economic development contribute to sex differences in ischaemic heart disease mortality? Hong Kong as a natural experiment using a case-control study

BACKGROUND

The male excess risk of premature ischemic heart disease (IHD) mortality may be partially due to an unknown macro-environmental influence associated with economic development. We examined whether excess male risk of IHD mortality was higher with birth in an economically developed environment.

METHODS

We used multivariable logistic regression in a population-based case-control study of all adult deaths in Hong Kong Chinese in 1998 to compare sex differences in IHD mortality (1,189 deaths in men, 1,035 deaths in women and 20,842 controls) between Hong Kong residents born in economically developed Hong Kong or in contemporaneously undeveloped Guangdong province in China.

RESULTS

Younger (35-64 years) native-born Hong Kong men had a higher risk of IHD death than such women (odds ratio 2.91, 95% confidence interval 1.66 to 5.13), adjusted for age, socio-economic status and lifestyle. There was no such sex difference in Hong Kong residents who had migrated from Guangdong. There were no sex differences in pneumonia deaths by birth place.

CONCLUSION

Most of these people migrated as young adults; we speculate that environmentally mediated differences in pubertal maturation (when the male disadvantage in lipids and fat patterning emerges) may contribute to excess male premature IHD mortality in developed environments.

Risk of lung cancer following exposure to carbon black, titanium dioxide and talc: results from two case-control studies in Montreal

The International Agency for Research on Cancer (IARC) recently evaluated the carcinogenicity of three poorly soluble weakly-toxic substances: carbon black, titanium dioxide and talc. Though there is evidence of carcinogenity in experimental animals for these substances, the evidence in humans is sparse and equivocal. In the context of two large population based case-control studies of lung cancer carried out in Montreal, we were able to study the possible relationships between the exposure to each of these substances and subsequent risk of lung cancer. We were able to distinguish talc used for industrial purposes from that used for cosmetic purposes. Interviews for Study I were conducted in 1979-1986 (857 cases, 533 population controls, 1,349 cancer controls) and interviews for Study II were conducted in 1996-2001 (1,236 cases and 1,512 controls). Detailed lifetime job histories were elicited, and a team of hygienists and chemists evaluated the evidence of exposure to a host of occupational substances. Lung cancer risk was analysed in relation to each exposure, adjusting for several potential confounders, including smoking. Subjects with occupational exposure to carbon black, titanium dioxide, industrial talc and cosmetic talc did not experience any detectable excess risk of lung cancer. The results are consistent with the recent evaluations of the IARC Monographs.