Potential misinterpretations caused by collapsing upper categories of comorbidity indices: An illustration from a cohort of older breast cancer survivors

BACKGROUND: Comorbidity indices summarize complex medical histories into concise ordinal scales, facilitating stratification and regression in epidemiologic analyses. Low subject prevalence in the highest strata of a comorbidity index often prompts combination of upper categories into a single stratum (\u27collapsing\u27). OBJECTIVE: We use data from a breast cancer cohort to illustrate potential inferential errors resulting from collapsing a comorbidity index. METHODS: Starting from a full index (0, 1, 2, 3, and \u3e/=4 comorbidities), we sequentially collapsed upper categories to yield three collapsed categorizations. The full and collapsed categorizations were applied to analyses of (1) the association between comorbidity and all-cause mortality, wherein comorbidity was the exposure; (2) the association between older age and all-cause mortality, wherein comorbidity was a candidate confounder or effect modifier. RESULTS: Collapsing the index attenuated the association between comorbidity and mortality (risk ratio, full versus dichotomized categorization: 4.6 vs 2.1), reduced the apparent magnitude of confounding by comorbidity of the age/mortality association (relative risk due to confounding, full versus dichotomized categorization: 1.14 vs 1.09), and obscured modification of the association between age and mortality on both the absolute and relative scales. CONCLUSIONS: Collapsing categories of a comorbidity index can alter inferences concerning comorbidity as an exposure, confounder and effect modifier

Motivation and mortality in older women with early stage breast cancer: A longitudinal study with ten years of follow-up.

OBJECTIVES The Getting Out of Bed Scale (GOB) was validated as a health-related quality of life (HRQoL) variable in older women with early stage breast cancer, suggesting its potential as a concise yet powerful measure of motivation. The aim of our project was to assess the association between GOB and mortality over 10years of follow-up. MATERIALS AND METHODS We studied 660 women ≥65-years old diagnosed with stage I-IIIA primary breast cancer. Data were collected over 10years of follow-up from interviews, medical records, and death indexes. RESULTS Compared to women with lower GOB scores, women with higher GOB had an unadjusted hazard ratio (HR) of all-cause mortality of 0.78 at 5years, 95% confidence interval (CI) (0.52, 1.19) and 0.77 at 10years, 95%CI (0.59, 1.00). These associations diminished after adjusting for age and stage of breast cancer, and further after adjusting for other HRQoL variables including physical function, mental health, emotional health, psychosocial function, and social support. Unadjusted HRs of breast cancer-specific mortality were 0.92, 95%CI (0.49, 1.74), at 5years, and 0.82, 95%CI (0.52, 1.32), at 10years. These associations also decreased in adjusted models. CONCLUSION Women with higher GOB scores had a lower hazard of all-cause mortality in unadjusted analysis. This effect diminished after adjusting for confounding clinical and HRQoL variables. GOB is a measure of motivation that may not be independently associated with cancer mortality, but reflects other HRQoL variables making it a potential outcome to monitor in older patients with cancer

Comparison of Different Approaches to Confounding Adjustment in a Study on the Association of Antipsychotic Medication With Mortality in Older Nursing Home Patients

Selective prescribing of conventional antipsychotic medication (APM) to frailer patients is thought to have led to overestimation of the association with mortality in pharmacoepidemiologic studies relying on claims data. The authors assessed the validity of different analytic techniques to address such confounding. The cohort included 82,012 persons initiating APM use after admission to a nursing home in 45 states with 2001–2005 Medicaid/Medicare data, linked to clinical data (Minimum Data Set) and institutional characteristics. The authors compared the association between APM class and 180-day mortality with multivariate outcome modeling, propensity score (PS) adjustment, and instrumental variables. The unadjusted risk difference (per 100 patients) of 10.6 (95% confidence interval (CI): 9.4, 11.7) comparing use of conventional medication with atypical APM was reduced to 7.8 (95% CI: 6.6, 9.0) and 7.0 (95% CI: 5.8, 8.2) after PS adjustment and high-dimensional PS (hdPS) adjustment, respectively. Results were similar in analyses limited to claims-based Medicaid /Medicare variables (risk difference = 8.2 for PS, 7.1 for hdPS). Instrumental-variable estimates were imprecise (risk difference = 8.8, 95% CI: −1.3, 19.0) because of the weak instrument. These results suggest that residual confounding has a relatively small impact on the effect estimate and that hdPS methods based on claims alone provide estimates at least as good as those from conventional analyses using claims enriched with clinical information

Automated inter-rater reliability assessment and electronic data collection in a multi-center breast cancer study

<p>Abstract</p> <p>Background</p> <p>The choice between paper data collection methods and electronic data collection (EDC) methods has become a key question for clinical researchers. There remains a need to examine potential benefits, efficiencies, and innovations associated with an EDC system in a multi-center medical record review study.</p> <p>Methods</p> <p>A computer-based automated menu-driven system with 658 data fields was developed for a cohort study of women aged 65 years or older, diagnosed with invasive histologically confirmed primary breast cancer (N = 1859), at 6 Cancer Research Network sites. Medical record review with direct data entry into the EDC system was implemented. An inter-rater and intra-rater reliability (IRR) system was developed using a modified version of the EDC.</p> <p>Results</p> <p>Automation of EDC accelerated the flow of study information and resulted in an efficient data collection process. Data collection time was reduced by approximately four months compared to the project schedule and funded time available for manuscript preparation increased by 12 months. In addition, an innovative modified version of the EDC permitted an automated evaluation of inter-rater and intra-rater reliability across six data collection sites.</p> <p>Conclusion</p> <p>Automated EDC is a powerful tool for research efficiency and innovation, especially when multiple data collection sites are involved.</p

Risk of venous thromboembolism after total hip and knee replacement in older adults with comorbidity and co-occurring comorbidities in the Nationwide Inpatient Sample (2003-2006)

<p>Abstract</p> <p>Background</p> <p>Venous thromboembolism is a common, fatal, and costly injury which complicates major surgery in older adults. The American College of Chest Physicians recommends high potency prophylaxis regimens for individuals undergoing total hip or knee replacement (THR or TKR), but surgeons are reluctant to prescribe them due to fear of excess bleeding. Identifying a high risk cohort such as older adults with comorbidities and co-occurring comorbidities who might benefit most from high potency prophylaxis would improve how we currently perform preoperative assessment.</p> <p>Methods</p> <p>Using the Nationwide Inpatient Sample, we identified older adults who underwent THR or TKR in the U.S. between 2003 and 2006. Our outcome was VTE, including any pulmonary embolus or deep venous thrombosis. We performed multivariate logistic regression analyses to assess the effects of comorbidities on VTE occurrence. Comorbidities under consideration included coronary artery disease, congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), diabetes, and cerebrovascular disease. We also examined the impact of co-occurring comorbidities on VTE rates.</p> <p>Results</p> <p>CHF increased odds of VTE in both the THR cohort (OR = 3.08 95% CI 2.05-4.65) and TKR cohort (OR = 2.47 95% CI 1.95-3.14). COPD led to a 50% increase in odds in the TKR cohort (OR = 1.49 95% CI 1.31-1.70). The data did not support synergistic effect of co-occurring comorbidities with respect to VTE occurrence.</p> <p>Conclusions</p> <p>Older adults with CHF undergoing THR or TKR and with COPD undergoing TKR are at increased risk of VTE. If confirmed in other datasets, these older adults may benefit from higher potency prophylaxis.</p

Older Breast Cancer Survivors: Factors Associated with Self-reported Symptoms of Persistent Lymphedema Over 7 years of Follow-up

Lymphedema of the arm is a common complication of breast cancer with symptoms that can persist over long periods of time. For older women (over 50% of breast cancer cases) it means living with the potential for long-term complications of persistent lymphedema in conjunction with the common diseases and disabilities of aging over survivorship. We identified women > or =65 years diagnosed with primary stage I-IIIA breast cancer. Data were collected over 7 years of follow-up from consenting patients' medical records and telephone interviews. Data collected included self-reported symptoms of persistent lymphedema, breast cancer characteristics, and selected sociodemographic and health-related characteristics. The overall prevalence of symptoms of persistent lymphedema was 36% over 7 years of follow-up. Having stage II or III (OR = 1.77, 95% CI: 1.07-2.93) breast cancer and having a BMI >30 (OR = 3.04, 95% CI: 1.69-5.45) were statistically significantly predictive of symptoms of persistent lymphedema. Women > or =80 years were less likely to report symptoms of persistent lymphedema when compared to younger women (OR = 0.44, 95% CI: 0.18-0.95). Women with symptoms of persistent lymphedema consistently reported worse general mental health and physical function. Symptoms of persistent lymphedema were common in this population of older breast cancer survivors and had a noticeable effect on both physical function and general mental health. Our findings provide evidence of the impact of symptoms of persistent lymphedema on the quality of survivorship of older women. Clinical and research efforts focused on risk factors for symptoms of persistent lymphedema in older breast cancer survivors may lead to preventative and therapeutic measures that help maintain their health and well-being over increasing periods of survivorship