Patterns of statin initiation and continuation in patients with breast or colorectal cancer, towards end-of-life

Risk of thromboembolism according to statin treatment in patients with cancer: A nationwide nested case-control study

BACKGROUND

Thromboembolic events exhibit increased prevalence in patients with cancer and can negatively affect prognoses. We investigated whether statin treatment would reduce thromboembolic risk in patients with cancer.

METHODS

We conducted a nested case-control study using a Korean nationwide health claims database. The study included patients newly diagnosed with cancer without a prior history of cardiovascular disease between 2014 and 2016. Cases who developed arterial thromboembolism (ATE) or venous thromboembolism (VTE) after cancer diagnosis and three individually matched controls were selected. Conditional logistic regression was used to assess the association between thromboembolic risk and statin therapy after cancer diagnosis.

RESULTS

Among 455,805 newly diagnosed patients with cancer followed for a mean of 4.3 ± 2.0 years, 22,249 patients developed thromboembolic events (ATE: 6341, VTE: 15,908), resulting in an incidence rate of 1133 per 100,000 person-years. The nested case-control study included 21,289 cases with thromboembolic events and 63,867 controls. Statin use was less frequent in the case group (18.0 % vs. 23.7 %). Statin treatment was associated with a lower risk of thromboembolic events (adjusted odds ratio [OR] 0.70; 95 % confidence interval [CI] 0.67-0.73). This association was observed for both ATE (adjusted OR 0.68; 95 % CI 0.63-0.74) and VTE (adjusted OR 0.71; 95 % CI 0.67-0.75). Longer statin use and better adherence were also associated with lower risk for thromboembolic events. Statin treatment was significantly associated with fewer thromboembolic events in most cancer types.

CONCLUSIONS

Statin use was associated with lower risk for thromboembolic events in patients newly diagnosed with cancer.

Factors associated with statin discontinuation near end of life in a Danish primary health care cohort

BACKGROUND

Long-term preventive treatment such as treatment with statins should be reassessed among patients approaching end of life. The aim of the study was to describe the rate of discontinuation of statin treatment and factors associated with discontinuation in the 6 months before death.

METHODS

This study is a retrospective cohort study using national registers and blood test results from primary health care patients. Patients in the Copenhagen municipality, Denmark who died between 1997 and 2018 and were statin users during the 10-year period before death were included. We calculated the proportion who remained statin users in the 6-month period before death. Factors associated with discontinuation were tested using logistic regression.

RESULTS

A total of 55,591 decedents were included. More patients continued treatment (64%, n = 35,693) than discontinued (36%, n = 19,898) the last 6 months of life. The 70 and 80 age groups had the lowest odds of discontinuing compared to the 90 (OR 1.59, 95% CI 0.93-2.72) and 100 (OR 3.11, 95% CI 2.79-3.47) age groups. Increasing comorbidity score (OR 0.89, 95% CI 0.87; 0.90 per 1-point increase) and use of statins for secondary prevention (OR 0.89, 95% CI 0.85; 0.93) reduced the likelihood of discontinuation as did a diagnosis of dementia, heart failure, or cancer.

CONCLUSION

A substantial portion of patients continued statin treatment near end of life. Efforts to promote rational statin use and discontinuation are required among patients with limited life expectancy, including establishing clear, practical recommendations about statin discontinuation, and initiatives to translate recommendations into clinical practice.

Pharmacoepidemiological Evaluation in Prostate Cancer-Common Pitfalls and How to Avoid Them

Simple Summary

Pharmacoepidemiologic research provides opportunities to evaluate how commonly used drug groups, such as cholesterol-lowering drugs, may affect the prostate cancer risk or mortality. However, such studies need to be carefully designed in order to avoid biases caused by systematic differences between medication users and non-users. Similarly, data must be carefully analyzed and interpreted while acknowledging possible biases that can lead to erroneous conclusions. Here, we review common pitfalls in such studies and describe ways to avoid them in an effort to aid future research.

Abstract

Pharmacoepidemiologic research provides opportunities to evaluate how commonly used drug groups, such as cholesterol-lowering or antidiabetic drugs, may affect the prostate cancer risk or mortality. This type of research is valuable in estimating real-life drug effects. Nonetheless, pharmacoepidemiological studies are prone to multiple sources of bias that mainly arise from systematic differences between medication users and non-users. If these are not appreciated and properly controlled for, there is a risk of obtaining biased results and reaching erroneous conclusions. Therefore, in order to improve the quality of future research, we describe common biases in pharmacoepidemiological studies, particularly in the context of prostate cancer research. We also list common ways to mitigate these biases and to estimate causality between medication use and cancer outcomes.

The association of serum lipid levels with colorectal cancer recurrence

BACKGROUND

Biologic and epidemiologic evidence suggests that tumor cells depend on reprogrammed lipid metabolic function for survival and growth. Lipids may promote tumor recurrence by providing energy needed for proliferation. Studies have found associations of serum lipids with cancer incidence, mortality, and disease-free mortality, though they have yet to evaluate the prognostic potential of serum lipids for colorectal cancer (CRC) recurrence.

METHODS

341 Danish CRC patients who underwent surgical resection were actively followed between 2003-2011 from date of surgery until December 31, 2012, or death. Serum lipids including low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG), were collected at regular intervals. Lipids were assigned as time-varying exposures evaluated with a one-year lag. Cox proportional hazards models were used to assess recurrence rate, adjusting for clinically relevant covariates. A restricted analysis was performed in a group of non-statin users (n = 236).

RESULTS

Among 341 CRC patients, increased HDL-C appeared to have a beneficial impact on recurrence-free survival (RFS) for CRC patients, especially among statin users (hazard ratio [HR] for 0.1 mmol/L increase = 0.58; 95 % confidence interval [CI]: 0.43, 0.78). Increased LDL-C and TG were not associated with RFS. Increased lipids showed a near-null effect on CRC recurrence [e.g. HR (95 % CI) for 0.1 mmol/L increase LDL = 1.01 (0.97, 1.19)] among non-statin users.

CONCLUSION

Serum lipid levels of LDL-C and TG do not appear to be associated with CRC recurrence. Further investigation of the role of HDL-C in CRC recurrence may be of interest based on the suggestive inverse association observed here.

Fitting Marginal Structural and G-Estimation Models Under Complex Treatment Patterns: Investigating the Association Between De Novo Vitamin D Supplement Use After Breast Cancer Diagnosis and All-Cause Mortality Using Linked Pharmacy Claim and Registry Data

Studies have shown that accounting for time-varying confounding through time-dependent Cox proportional hazards models may provide biased estimates of the causal effect of treatment when the confounder is also a mediator. We explore 2 alternative approaches to addressing this problem while examining the association between vitamin D supplementation initiated after breast cancer diagnosis and all-cause mortality. Women aged 50-80 years were identified in the National Cancer Registry Ireland (n = 5,417) between 2001 and 2011. Vitamin D use was identified from linked prescription data (n = 2,570). We sought to account for the time-varying nature of vitamin D use and time-varying confounding by bisphosphonate use using 1) marginal structural models (MSMs) and 2) G-estimation of structural nested accelerated failure-time models (SNAFTMs). Using standard adjusted Cox proportional hazards models, we found a reduction in all-cause mortality in de novo vitamin D users compared with nonusers (hazard ratio (HR) = 0.84, 95% confidence interval (CI): 0.73, 0.99). Additional adjustment for vitamin D and bisphosphonate use in the previous month reduced the hazard ratio (HR = 0.45, 95% CI: 0.33, 0.63). Results derived from MSMs (HR = 0.44, 95% CI: 0.32, 0.61) and SNAFTMs (HR = 0.45, 95% CI: 0.34, 0.52) were similar. Utilizing MSMs and SNAFTMs to account for time-varying bisphosphonate use did not alter conclusions in this example.

Developing Predictive Models to Determine Patients in End-of-Life Care in Administrative Datasets

Introduction

In observational studies with mortality endpoints, one needs to consider how to account for subjects whose interventions appear to be part of ‘end-of-life’ care.

Objective

The objective of this study was to develop a diagnostic predictive model to identify those in end-of-life care at the time of a drug exposure.

Methods

We used data from four administrative claims datasets from 2000 to 2017. The index date was the date of the first prescription for the last new drug subjects received during their observation period. The outcome of end-of-life care was determined by the presence of one or more codes indicating terminal or hospice care. Models were developed using regularized logistic regression. Internal validation was through examination of the area under the receiver operating characteristic curve (AUC) and through model calibration in a 25% subset of the data held back from model training. External validation was through examination of the AUC after applying the model learned on one dataset to the three other datasets.

Results

The models showed excellent performance characteristics. Internal validation resulted in AUCs ranging from 0.918 (95% confidence interval [CI] 0.905–0.930) to 0.983 (95% CI 0.978–0.987) for the four different datasets. Calibration results were also very good, with slopes near unity. External validation also produced very good to excellent performance metrics, with AUCs ranging from 0.840 (95% CI 0.834–0.846) to 0.956 (95% CI 0.952–0.960).

Conclusion

These results show that developing diagnostic predictive models for determining subjects in end-of-life care at the time of a drug treatment is possible and may improve the validity of the risk profile for those treatments.

Electronic supplementary material

The online version of this article (10.1007/s40264-020-00906-7) contains supplementary material, which is available to authorized users.

The Association Between Statin Use After Diagnosis and Mortality Risk in Patients With Esophageal Cancer: A Retrospective Cohort Study of United States Veterans

OBJECTIVE

Statins may reduce mortality from esophageal cancer by both reducing incidence but also improving prognosis. However, prior studies of statin use and mortality have reported conflicting results.

METHODS

We identified 7882 patients with esophageal adenocarcinoma (EAC) and 3868 with esophageal squamous cell carcinoma (ESCC) from the VA Central Cancer Registry diagnosed between 2002 and 2016. We identified prescriptions for statins that were filled before and after cancer diagnosis. Time-dependent Cox regression models were used to calculate hazard ratios (HR) and 95% CIs for mortality risk. We used a time-varying exposure to avoid immortal-time bias and a 3 month lag (following patients from 3 months after cancer diagnosis) to reduce reverse causation. A sensitivity analysis was conducted varying the lag duration between date of cancer diagnosis and start of follow-up.

RESULTS

Statin use after diagnosis was recorded in 27.4% of EAC and 17.1% of ESCC patients. In EAC patients, statin use after diagnosis was associated with a decreased risk of cancer specific (HR, 0.79; 95% CI 0.70-0.88) and all-cause mortality (HR, 0.80; 95% CI 0.74-0.86). Similarly, statin use after diagnosis of ESCC was associated with a decreased risk of cancer specific (HR, 0.77; 95% CI 0.63-0.92) and all-cause mortality (HR, 0.83; 95% CI 0.74-0.95). The inverse associations were attenuated towards the null with a 6-month lag.

CONCLUSIONS

Post-diagnosis statin use was associated with reduced mortality in esophageal cancer patients; however, the effect may be partially due to reverse causality as patients with poor prognosis are unlikely to initiate statin therapy.

De novo vitamin D supplement use post-diagnosis is associated with breast cancer survival

PURPOSE

Experimental laboratory data have indicated a protective effect of vitamin D on breast cancer progression, while epidemiological evidence is growing. Using pharmacy claims data, this study investigates the association between vitamin D supplement use initiated after a breast cancer diagnosis and associated mortality.

METHODS

Women aged 50-80 years with a record of invasive breast cancer were identified on the National Cancer Registry Ireland database (n = 5417). Initiation of de novo vitamin D post-diagnosis was identified from linked national prescription data (n = 2581, 49%). Multivariate Cox proportional hazards models were used to estimate adjusted HRs (95% CIs) for breast cancer-specific mortality.

RESULTS

There was a 20% reduction in breast cancer-specific mortality in de novo vitamin D users (modelled as a time-varying variable) compared to non-users (HR 0.80; 95% CI 0.64-0.99, p = 0.048) and the reduction was greater at 49% (HR 0.51; 95% CI 0.34-0.74, p < 0.001), if vitamin D was initiated soon after the breast cancer diagnosis (within 6 months).

CONCLUSIONS

In this large national breast cancer cohort, de novo vitamin D use post-diagnosis was found to be associated with a reduction in breast cancer-specific mortality. Vitamin D, therefore, has the potential as a non-toxic and inexpensive agent to improve survival in breast cancer patients. Findings support the need for RCTs exploring the effect of vitamin D supplementation on breast cancer survival.

Low-Dose Aspirin Use Does Not Increase Survival in 2 Independent Population-Based Cohorts of Patients With Esophageal or Gastric Cancer

BACKGROUND & AIMS

Preclinical studies have shown aspirin to have anticancer properties and epidemiologic studies have associated aspirin use with longer survival times of patients with cancer. We studied 2 large cohorts to determine the association between aspirin use and cancer-specific mortality in patients with esophageal or gastric cancer.

METHODS

We performed a population-based study using cohorts of patients newly diagnosed with esophageal or gastric cancer, identified from cancer registries in England from 1998 through 2012 and the Scottish Cancer Registry from 2009 through 2012. Low-dose aspirin prescriptions were identified from linkages to the United Kingdom Clinical Research Practice Datalink in England and the Prescribing Information System in Scotland. Deaths were identified from linkage to national mortality records, with follow-up until September 2015 in England and January 2015 in Scotland. Time-dependent Cox regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer-specific mortality by low-dose aspirin use after adjusting for potential confounders. Meta-analysis was used to pool results across the 2 cohorts.

RESULTS

The combined English and Scottish cohorts contained 4654 patients with esophageal cancer and 3833 patients with gastric cancer, including 3240 and 2392 cancer-specific deaths, respectively. The proportions surviving 1 year, based on cancer-specific mortality, were similar in aspirin users vs non-users after diagnosis with esophageal cancer (48% vs 50% in England and 49% vs 46% in Scotland, respectively) or gastric cancer (58% vs 57% in England and 59% vs 55% in Scotland, respectively). There was no association between postdiagnosis use of low-dose aspirin and cancer-specific mortality among patients with esophageal cancer (pooled adjusted HR, 0.98; 95% CI, 0.89-1.09) or gastric cancer (pooled adjusted HR, 0.96; 95% CI, 0.85-1.08). Long-term aspirin use was not associated with cancer-specific mortality after diagnosis of esophageal cancer (pooled adjusted HR, 1.03; 95% CI, 0.85-1.25) or gastric cancer (pooled adjusted HR, 1.06; 95% CI, 0.85-1.32).

CONCLUSIONS

In analyses of 2 large independent cohorts in the United Kingdom, low-dose aspirin usage was not associated with increased survival of patients diagnosed with esophageal or gastric cancer.

Low-dose aspirin use and survival in colorectal cancer: results from a population-based cohort study

BACKGROUND

Aspirin has been proposed as a novel adjuvant agent in colorectal cancer (CRC). Six observational studies have reported CRC-specific survival outcomes in patients using aspirin after CRC diagnosis but the results from these studies have been conflicting. Using a population-based cohort design this study aimed to assess if low-dose aspirin use after diagnosis reduced CRC-specific mortality.

METHODS

A cohort of 8391 patients with Dukes' A-C CRC (2009-2012) was identified from the Scottish Cancer Registry and linked to national prescribing and death records. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for CRC-specific mortality were calculated using time-dependent Cox regression.

RESULTS

There were 1064 CRC-specific deaths after a median follow-up of 3.6 years. Post-diagnostic low-dose aspirin use was not associated with a reduction in CRC-specific mortality either before or after adjustment for confounders (adjusted HR = 1.17, 95% CI 1.00-1.36). In sensitivity analysis pre-diagnostic low-dose aspirin was also not associated with reduced CRC-specific mortality (adjusted HR = 0.96, 95% CI 0.88-1.05).

CONCLUSION

Low-dose aspirin use, either before or after diagnosis, did not prolong survival in this population-based CRC cohort.

Pre-diagnostic statin use, lymph node status and mortality in women with stages I-III breast cancer

Background:

Recent meta-analyses suggest that pre-diagnostic statin use is associated with reduced breast cancer-specific mortality. Studies have shown that high breast tumour expression of the statin target (3-hydroxy-3-methylglutaryl coenzyme-A reductase) is associated with lymph-node negative cancer. Therefore, we examined the association between pre-diagnostic statin use and; lymph node status, breast cancer-specific and all-cause mortality.

Methods:

Women with stages I–III breast cancer were identified from the National Cancer Registry of Ireland (N=6314). Pre-diagnostic statin users were identified from linked prescription claims data (N=2082). Relative risks were estimated for associations between pre-diagnostic statin use and lymph node status. Hazard ratios (HR) were estimated for associations between pre-diagnostic statin use and breast cancer-specific and all-cause mortality.

Results:

Pre-diagnostic statin use was not associated with lymph node negative status at diagnosis. In multivariate analyses, pre-diagnostic statin use was associated with reduced all-cause (HR 0.78 95% confidence interval (CI) 0.69, 0.89) and breast cancer-specific mortality (HR 0.81 95% CI 0.68, 0.96). This reduction in cancer-specific mortality was greatest in statin-users with oestrogen (ER) receptor-positive tumours (HR 0.69 95% CI 0.55, 0.85).

Conclusion:

Patients with pre-diagnostic statin exposure had a significant reduction in breast cancer-specific mortality, which was even more pronounced in women with ER+ tumours.