Early discontinuation of endocrine therapy for breast cancer: who is at risk in clinical practice?

Imatinib Adherence and Persistence in Patients with Chronic Myeloid Leukemia in Belgium: Evidence from Real-World Data

Purpose

Imatinib adherence and persistence are key components of the successful treatment of Chronic Myeloid Leukemia (CML). In Belgium, there is no study assessing these behaviors at a national level. Our study aimed to provide the first nationwide measure and to identify associated pharmacy-based predictors (age, gender, comorbidities). We also assessed mortality and transplantation incidence according to adherence status.

Methods

Based on medico-administrative database linkage, we identified a retrospective Belgian cohort of 1194 patients diagnosed with CML between 2004 and 2016 and treated with imatinib. Adherence was measured over 24 months, considering the proportion of days covered (PDC). Persistence was measured as the time until discontinuation (gap of ≥90 days). Multivariable Poisson regression models with robust standard error were conducted to identify predictors associated with adherence (≥90% PDC). To identify factors associated with persistence, a multivariable Cox regression was performed.

Results

At six months, 60.3% of patients were adherent, declining to 41.5% at 12 months, and to 30.1% at two-year follow-up (n=998). Adherence was greater at a younger age (eg 31-40 years vs ≥75 years, adjusted prevalence ratio (aPR) 1.73; 95% confidence interval (CI): 1.09-2.77) and among patients with no comorbidity (0 vs ≥2 comorbidities (aPR 1.56; 95% CI: 1.11-2.19). The median persistence was 334.5 days (Q1:200-Q3:505.5); persistence at 24 months was 83.6% (n=998). Only age was associated with higher risk of discontinuation, with adjusted hazard ratio (aHR) of 6.05 for patients ≥75 years (95% CI: 5.52-6.58). Transplants and deaths mainly occurred in patients defined as non-adherent at 24 months.

Conclusion

This Belgian nationwide representative study revealed a critical low level of imatinib adherence, which decreased over time even though persistence was high at six months. We pinpointed pharmacy-based predictors that were easily identifiable by health care stakeholders in order to undertake interventions to improve adherence.

Genitourinary syndrome of menopause in patients with breast cancer treated by hormonotherapy: women's perception in ITAC, a French web-based survey

OBJECTIVE

To describe frequency, intensity and impact of genito-urinary syndrome of menopause (GUSM) in breast cancer (BC) survivors receiving hormonotherapy (HT).

METHODS

Web-based survey hosted on the Seintinelles website (database of patients and caregivers). Specific questionnaire of 43 questions, including sociodemographic characteristics, history of BC, characteristics of HT, side effects other than GUSM, symptoms of GUSM (frequency, intensity, treatment, and impact) and overall expectations regarding treatment.

RESULTS

Among 1157 participants, 96.4% had at least one GUSM symptom. Percentages with at least one urinary, gynecological, or sexual symptom were 56.0%, 85.6% and 86.1% respectively while 70.3% and 10% declared at least 5 and 10 symptoms respectively. Mean (SD) and median (range) numbers of symptoms were 5.9 (2.8) and 6 (0-14) respectively. Most frequently reported symptoms were decreased desire (77.8%), decreased arousal (71.4%), and vaginal dryness 68.4%). On a scale from 0 (no impact) to 10 (maximal impact), the most important impact was reported for sexual life (mean: 6.6±3.5) followed by psychological condition/self-image (mean 5.4±3.1), and relations with partners (mean: 5.1±3.4). Only 13.6% of participants had received information on GUSM prior to the survey.

CONCLUSIONS

GUSM remains underdiagnosed and underestimated in BC survivors who receive HT, although it is among most frequent and disabling side effects of HT. Awareness should be increased among physicians, along with information to women. Early detection and treatment of symptoms and prophylaxis of GUSM in at-risk women should be implemented.

Feasibility of Symptom Monitoring During the First Year of Endocrine Therapy for Early Breast Cancer Using Patient-Reported Outcomes Collected via Smartphone App

PURPOSE

Treatment-associated symptoms drive early discontinuation of adjuvant endocrine therapy (ET) for breast cancer. We hypothesized that symptom monitoring with electronic patient-reported outcomes (ePROs) during adjuvant ET will enhance symptom detection, symptom management, and persistence.

METHODS

Eligible patients were initiating ET for stage 0-III breast cancer. Participants completed ePRO surveys via smartphone at baseline and 1, 3, 6, and 12 months. Measures included Patient-Reported Outcomes Measurement Information System Anxiety, Depression, Fatigue, and Vaginal Discomfort; plus Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events items assessing joint pain, hot flashes, vaginal dryness, concentration problems, and memory problems. Scores surpassing prespecified thresholds triggered alerts, and recommended symptom management pathways were provided to clinicians. The primary objective was to evaluate feasibility, assessed by survey completion rates, with targets of >65% for the baseline survey and ≥1 follow-up survey during the first 6 months. Secondary objectives included 12-month ET discontinuation rate (target: ≤15%), describing symptoms and evaluating pathway implementation.

RESULTS

Among 250 participants, 73.2% completed the baseline survey and 69.6% completed ≥1 follow-up survey during the first 6 months. Thirty-one percent of participants had ≥1 symptom alert at baseline and 74% had ≥1 symptom alert during follow-up. The proportions of participants for whom pathway-concordant symptom management was documented at each time point ranged from 12.8% to 36.6%. Twenty-eight participants (11.2%) discontinued ET by 12 months.

CONCLUSION

Symptom monitoring with ePROs during adjuvant ET is feasible. Despite infrequent documentation of pathway-concordant symptom management after symptom alerts, ePROs were associated with favorable short-term ET persistence.

Resistance to Resilience: Understanding Post-surgical Hormone Therapy in Breast Cancer Care

Breast cancer is one of the most common types of cancer affecting women worldwide. Over the years, breast cancer has become a major public health concern, and its incidence is rising globally. The treatment of breast cancer does not stop with surgical intervention, but adjuvant therapies are administered to improve patient outcomes post-surgery based on the type of breast cancer diagnosed. This review focuses on the value of hormone therapy (HT) in improving the prognosis of breast cancer patients and why adhering to adjuvant treatment post-surgery is difficult for patients. HT aims to reduce the chances of breast cancer recurrence after surgical treatment. Even though HT is life-saving, patients tend to not adhere to the therapy due to various factors such as side effects, age-related issues, and socioeconomic status. Most patients stop adhering to the therapy as the duration can be as long as 5-10 years, and the quality of life is greatly impacted due to the side effects of the treatment. This review examines the possible factors leading to non-adherence to HT and tries to propose possible interventions that might improve patient compliance with the treatment. This article not only focuses on the impact of side effects of HT on patients' quality of life but also tries to understand the problems faced by breast cancer patients in adhering to HT.

Adherence to adjuvant tamoxifen and associated factors in breast cancer survivors

PURPOSE

Adjuvant endocrine therapy reduces the recurrence and mortality of early hormone receptor-positive breast cancer in both pre- and postmenopausal women. The aim of this study was to investigate adjuvant tamoxifen adherence and associated factors in breast cancer survivors.

METHODS

This descriptive, prospective study was conducted in 2019-2020 with the participation of 531 women who survived breast cancer and were under follow-up at the Senology Institute of a hospital in Istanbul. Inclusion criteria were having completed treatment for early hormone receptor-positive breast cancer, being prescribed tamoxifen, and being 18 years or older. Data were collected using a patient information form and the Morisky Medication Adherence Scale-8 (MMAS-8).

RESULTS

The mean age of the participants was 44.9 ± 6.5 years, and the mean duration of tamoxifen use was 834.4 ± 685.7 days. The women's mean MMAS-8 score was 6.86 ± 1.39. Medication adherence was significantly positively correlated with current age (p = 0.006) and age at diagnosis (p = 0.002). There was a statistically significant difference between tamoxifen adherence according to participants' employment status (p = 0.028), chronic disease status (p = 0.018), loss of libido (p = 0.012), treatment-related changes in mood changes (p = 0.004), and having negative effects affecting daily life (p < 0.001).

CONCLUSION

Overall, breast cancer survivors in this study reported moderate adherence to tamoxifen. The women's individual characteristics and the adverse effects of treatment influenced medication adherence. Healthcare professionals can help increase adherence to this treatment, which reduces the risk of mortality, by explaining the importance of the medication, identifying and eliminating barriers to adherence, and informing women about evidence-based interventions to increase medication compliance.

Factors associated with initiation and continuation of endocrine therapy in women with hormone receptor-positive breast cancer

Background

Despite benefits of endocrine therapy (ET) for patients with hormone-receptor (HR)-positive breast cancer, many patients do not initiate or discontinue ET against recommendations.

Methods

We identified variables associated with ET initiation and continuation, analyzing pooled data from two longitudinal studies at a National Cancer Institute comprehensive cancer center in St. Louis, Missouri. The sample included 533 women with newly diagnosed, non-metastatic, HR-positive breast cancer who completed interviews at enrollment and 6, 12, and 24 months after definitive surgical treatment. Logistic regression models estimated the adjusted odds ratio and 95% confidence interval (aOR [95% CI]) for each of self-reported ET initiation by the 12-month interview and continuation for ≥12 months by the 24-month interview in association with self-reported diabetes, elevated depressed mood, menopausal-symptom severity and obesity, adjusting for race, age, insurance status, chemotherapy, and radiation therapy.

Results

Overall, 81.4% (434/533) of patients initiated ET, and 86.5% (371/429) continued ET ≥12 months. Patients with diabetes had lower odds of initiating ET (0.50 [0.27-0.91]). Patients reporting greater menopausal-symptom severity had lower odds of continuing ET (0.72 [0.53-0.99]).

Conclusion

Efforts to increase ET initiation among patients with diabetes and better manage severe menopausal symptoms among ET users might promote ET continuation.

Clinical trial information

ClinicalTrials.gov: #NCT00929084.

Persistence with tamoxifen and aromatase inhibitors in Germany: a retrospective cohort study with 284,383 patients

PURPOSE

The aim of this study was to analyze the persistence of women on tamoxifen (TAM) and aromatase inhibitors (AIs) in Germany, and to investigate possible determinants of non-persistence.

METHODS

The present retrospective cohort study was based on the IQVIA longitudinal prescription database (LRx). The study included women with an initial prescription of TAM or AIs (anastrozole, letrozole, and exemestane) between January 2016 and December 2020 (index date). Kaplan-Meier analyses were performed to show the persistence for TAM and AI, using a therapy gap of 90 or 180 days, respectively. A multivariable Cox proportional hazards regression model was further used to estimate the relationship between non-persistence and drug prescription (AI versus TAM), age, and the specialty of the physician initiating therapy (gynecologist, oncologist, or general practitioner).

RESULTS

Up to 5 years after the index date, only 35.1% of AI and 32.5% of TAM patients were continuing therapy when therapy discontinuation was defined as at least 90 days without therapy. Using a 180-day therapy gap, 51.9% of AI and 50.4% of TAM patients remained on therapy after 5 years. Cox regression models reveal that initial therapy with TAM (HR 1.06, 95% CI 1.04-1.07), therapy initiation by oncologists (HR 1.09, 95% CI 1.07-1.11), or general practitioners (HR 1.24, 95% CI 1.21-1.27) and age ≤ 50 (HR 1.08, 95% CI 1.06-1.10) were significantly associated with an increased risk of therapy discontinuation.

CONCLUSION

Overall, the present study indicates that persistence rates are low in all age groups for both TAM and AI treatment. We found several factors (e.g., physician specialty, younger age, and type of endocrine therapy) to be associated with an increased risk for non-persistence.

Association of treatment-emergent symptoms identified by patient-reported outcomes with adjuvant endocrine therapy discontinuation

Many patients discontinue endocrine therapy for breast cancer due to intolerance. Identification of patients at risk for discontinuation is challenging. The minimal important difference (MID) is the smallest change in a score on a patient-reported outcome (PRO) that is clinically significant. We evaluated the association between treatment-emergent symptoms detected by worsening PRO scores in units equal to the MID with discontinuation. We enrolled females with stage 0-III breast cancer initiating endocrine therapy in a prospective cohort. Participants completed PROs at baseline, 3, 6, 12, 24, 36, 48, and 60 months. Measures included PROMIS pain interference, fatigue, depression, anxiety, physical function, and sleep disturbance; Endocrine Subscale of the FACT-ES; and MOS-Sexual Problems (MOS-SP). We evaluated associations between continuous PRO scores in units corresponding to MIDs (PROMIS: 4-points; FACT-ES: 5-points; MOS-SP: 8-points) with time to endocrine therapy discontinuation using Cox proportional hazards models. Among 321 participants, 140 (43.6%) initiated tamoxifen and 181 (56.4%) initiated aromatase inhibitor (AI). The cumulative probability of discontinuation was 23% (95% CI 18-27%) at 48 months. For every 5- and 4-point worsening in endocrine symptoms and sleep disturbance respectively, participants were 13 and 14% more likely to discontinue endocrine therapy respectively (endocrine symptoms HR 1.13, 95% CI 1.02-1.25, p = 0.02; sleep disturbance HR 1.14, 95% CI 1.01-1.29, p = 0.03). AI treatment was associated with greater likelihood of discontinuation than tamoxifen. Treatment-emergent endocrine symptoms and sleep disturbance are associated with endocrine therapy discontinuation. Monitoring for worsening scores meeting or exceeding the MID on PROs may identify patients at risk for discontinuation.

Factors influencing five-year adherence to adjuvant endocrine therapy in breast cancer patients: A systematic review

Purpose

This systematic review aimed to determine the rate and identify correlates of adherence and persistence over five years of treatment with adjuvant endocrine therapy in female breast cancer patients.

Methods

Relevant articles were identified from Medline, Embase, AMED, PsycINFO, International Pharmaceutical Abstracts, and APA PsycArticles. Studies that measured patient adherence in the implementation or persistence phase for a period of at least five years using objective or multiple measures of adherence and investigated correlates of adherence were included. The titles, abstracts and full articles were screened and reviewed by two authors and any discrepancies were discussed with a third author.

Results

Twenty-six studies were included. Mean rate of adherence at five-year for implementation phase was 66.2% (SD = 17.3%), and mean persistence was 66.8% (SD = 14.5%). On average, adherence decreased by 25.5% (SD = 9.3%) from the first to fifth year. Higher rate of adherence was observed through self-report in comparison to database or medical record. Older age, younger age, higher comorbidity index, depression and adverse effects were associated with lower adherence. Treatment with aromatase inhibitors, received chemotherapy, and prior medication use were associated with improved adherence.

Conclusion

Adherence to adjuvant endocrine therapy decreased from the first to fifth year of treatment. On average, one-third of patients were not adherent to treatment by the fifth year. Nineteen recurring factors were found to be significantly associated with long-term adherence in multiple studies. Further research using objective or multiple measures of adherence are needed to improve validity of results.

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On average, adherence fell by 25.5% from the first to the fifth year of treatment.

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Self-reported adherence may overestimate patient adherence.

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Nineteen recurring factors were associated with adherence.

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Having adverse effects was negatively associated with adherence.

Therapeutic Targeting of Minimal Residual Disease to Prevent Late Recurrence in Hormone-Receptor Positive Breast Cancer: Challenges and New Approaches

While the majority of breast cancers are diagnosed at a curable stage, approximately 20% of women will experience recurrence at a distant site during their lifetime. These metastatic recurrences are incurable with current therapeutic approaches. Over the past decade, the biologic mechanisms underlying these recurrences have been elucidated, establishing the existence of minimal residual disease in the form of circulating micrometastases and dormant disease, primarily in the bone marrow. Numerous technologies are now available to detect minimal residual disease (MRD) after breast cancer treatment, but it is yet unknown how to best target and eradicate these cells, and whether clearance of detectable disease prior to the formation of overt metastases can prevent ultimate progression and death. Clinical trials to test this hypothesis are challenging due to the rare nature of MRD in the blood and bone marrow, resulting in the need to screen a large number of survivors to identify those for study. Use of prognostic molecular tools may be able to direct screening to those patients most likely to harbor MRD, but the relationship between these predictors and MRD detection is as yet undefined. Further challenges include the lack of a definitive assay for MRD with established clinical utility, difficulty in selecting potential interventions due to limitations in understanding the biology of MRD, and the emotional impact of detecting MRD in patients who have completed definitive treatment and have no evidence of overt metastatic disease. This review provides a roadmap for tackling these challenges in the design and implementation of interventional clinical trials aimed at eliminating MRD and ultimately preventing metastatic disease to improve survival from this disease, with a specific focus on late recurrences in ER+ breast cancer.

Endocrine adherence in male versus female breast cancer: a seer-medicare review

PURPOSE

Breast cancer in men (BC-M) is almost exclusively hormone receptor positive. We conducted a large review of the SEER-Medicare linked database to compare endocrine therapy adherence, discontinuation, and survival outcomes of male versus female patients with breast cancer.

METHODS

Study data were obtained through the SEER-Medicare linked database. The study included patients age ≥ 65 years-old diagnosed with breast cancer between 2007 and 2015. The primary endpoints were rates of adherence and discontinuation of endocrine therapy (ET). Adherence was defined as a gap of less than 90 days in-between consecutive Medicare prescriptions. Discontinuation was defined as a gap of greater than 12 months in-between Medicare prescriptions. Secondary endpoint was the association of use of ET with overall survival (OS).

RESULTS

Of the 363 male patients on ET, 214 patients (59.0%) were adherent to the therapy, and 149 patients (41.0%) were nonadherent. Of the 20,722 females on ET, 10,752 (51.9%) were adherent to the therapy, and 9970 (48.1%) were nonadherent. 39 male patients (10.7%) discontinued therapy, while 324 (89.3%) did not discontinue therapy. 1849 female patients (8.9%) discontinued therapy, while 18,873 (91.1%) patients did not. Men were significantly more adherent than women (p = 0.008), but there was no significant difference in discontinuation among men and women (p = 0.228). Survival was significantly improved in both men (HR 0.77, 95% CI 0.60-0.99, p = 0.039) and women (HR 0.84, 95% CI 0.81-0.87, p < 0.001) on ET.

CONCLUSION

Identification of contributing factors impacting adherence and discontinuation is needed to allow physicians to address barriers to long term use of ET.

Endocrine Treatment for Breast Cancer Patients Revisited-History, Standard of Care, and Possibilities of Improvement

PURPOSE OF REVIEW

Due to the findings of current studies and the approval of novel substances for the therapy of hormone-receptor-positive breast cancer patients, the established standards of endocrine treatment are changing. The purpose of this review is to give an overview of the history of endocrine treatment, to clarify its role in the present standard of care, and to discuss the possibilities of improvement.

RECENT FINDINGS

Tamoxifen, aromatase inhibitors, and fulvestrant are the main drugs that have been used for decades in the therapy of hormone-receptor-positive breast cancer patients. However, since a relevant number of women suffer at some point from disease recurrence or progression, several novel substances are being investigated to overcome resistance mechanisms by interfering with certain signaling pathways, such as the PI3K/AKT/mTOR or the CDK4/6 pathways. mTOR and CDK4/6 inhibitors were the first drugs approved for this purpose and many more are in development.

SUMMARY

Endocrine treatment is one of the best tolerable cancer therapies available. Continuous investigation serves to improve patients' outcomes and modernize the current standard of care. Considering the resistance mechanisms and substances analyzed against these, endocrine treatment of hormone-receptor-positive breast cancer is on the brink of a new era.

Further Evidence That OPG rs2073618 Is Associated With Increased Risk of Musculoskeletal Symptoms in Patients Receiving Aromatase Inhibitors for Early Breast Cancer

Background

Aromatase inhibitors (AI) reduce recurrence and death in patients with early-stage hormone receptor-positive (HR +) breast cancer. Treatment-related toxicities, including AI-induced musculoskeletal symptoms (AIMSS), are common and may lead to early AI discontinuation. The objective of this study was to replicate previously reported associations for candidate germline genetic polymorphisms with AIMSS.

Methods

Women with stage 0-III HR + breast cancer initiating adjuvant AI were enrolled in a prospective clinic-based observational cohort. AIMSS were assessed by patient-reported outcomes (PRO) including the PROMIS pain interference and physical function measures plus the FACT-ES joint pain question at baseline and after 3 and 6 months. For the primary analysis, AIMSS were defined as ≥ 4-point increase in the pain interference T-score from baseline. Secondary AIMSS endpoints were defined as ≥ 4-point decrease in the physical function T-score from baseline and as ≥ 1-point increase on the FACT-ES joint pain question from baseline. The primary hypothesis was that TCL1A rs11849538 would be associated with AIMSS. Twelve other germline variants in CYP19A1, VDR, PIRC66, OPG, ESR1, CYP27B1, CYP17A1, and RANKL were also analyzed assuming a dominant genetic effect and prespecified direction of effect on AIMSS using univariate logistic regression with an unadjusted α = 0.05. Significant univariate associations in the expected direction were adjusted for age, race, body mass index (BMI), prior taxane, and the type of AI using multivariable logistic regression.

Results

A total of 143 participants with PRO and genetic data were included in this analysis, most of whom were treated with anastrozole (78%) or letrozole (20%). On primary analysis, participants carrying TCL1A rs11849538 were not more likely to develop AIMSS (odds ratio = 1.29, 95% confidence interval: 0.55-3.07, p = 0.56). In the statistically uncorrected secondary analysis, OPG rs2073618 was associated with AIMSS defined by worsening on the FACT-ES joint pain question (OR = 3.33, p = 0.004), and this association maintained significance after covariate adjustment (OR = 3.98, p = 0.003).

Conclusion

Carriers of OPG rs2073618 may be at increased risk of AIMSS. If confirmed in other cohorts, OPG genotyping can be used to identify individuals with HR + early breast cancer in whom alternate endocrine therapy or interventions to enhance symptom detection and implement strategies to reduce musculoskeletal symptoms may be needed.

Adherence trajectories of adjuvant endocrine therapy in the five years after its initiation among women with non-metastatic breast cancer: a cohort study using administrative databases

PURPOSE

Despite the benefits of adjuvant endocrine therapy (AET) for reducing recurrence and mortality risks after hormone-sensitive breast cancer, AET adherence is sub-optimal for a high proportion of women. However, little is known about long-term patterns of AET adherence over the minimally recommended 5 years. Our objectives were to: (1) identify 5-year AET adherence trajectory groups; (2) describe trajectory groups according to adherence measures traditionally used (i.e., Proportion of Days Covered); and (3) explore factors associated with trajectories.

METHODS

We conducted a 5-year cohort study using data from a French national study that included AET dispensing data. Women diagnosed with first non-metastatic breast cancer and having at least 1 AET dispensing in the 12 months after diagnosis were included. Group-based trajectory modeling was used to identify adherence trajectory groups by clustering similar patterns of monthly AET dispensing. Multinomial logistic regressions were used to identify factors associated with trajectories.

RESULTS

Among 674 women, five AET adherence trajectory groups were identified: (1) quick decline and stop (5.2% of women); (2) moderate decline and stop (6.4%); (3) slow decline (17.2%); (4) high adherence (30.0%); and (5) maintenance of very high adherence (41.2%). Mean 5-year Proportion of Days Covered varied from 10 to 97% according to trajectories. Women who did not receive chemotherapy or a personalized care plan were more likely to belong to trajectories where AET adherence declined and stopped.

CONCLUSION

Our results provide information on the diversity of longitudinal AET adherence patterns, the timing of decline and discontinuation and associated factors that could inform healthcare professionals.

The therapy is making me sick: how online portal communications between breast cancer patients and physicians indicate medication discontinuation

Objective

Online platforms have created a variety of opportunities for breast patients to discuss their hormonal therapy, a long-term adjuvant treatment to reduce the chance of breast cancer occurrence and mortality. The goal of this investigation is to ascertain the extent to which the messages breast cancer patients communicated through an online portal can indicate their potential for discontinuing hormonal therapy.

Materials and Methods

We studied the de-identified electronic medical records of 1106 breast cancer patients who were prescribed hormonal therapy at Vanderbilt University Medical Center over a 12-year period. We designed a data-driven approach to investigate patients' patterns of messaging with healthcare providers, the topics they communicated, and the extent to which these messaging behaviors associate with the likelihood that a patient will discontinue a prescribed 5-year regimen of therapy.

Results

The results indicates that messaging rate over time [hazard ratio (HR) = 1.373, P = 0.002], mentions of side effects (HR = 1.214, P = 0.006), and surgery-related topics (HR = 1.170, P = 0.034) were associated with increased risk of early medication discontinuation. In contrast, seeking professional suggestions (HR = 0.766, P = 0.002), expressing gratitude to healthcare providers (HR = 0.872, P = 0.044), and mentions of drugs used to treat side effects (HR = 0.807, P = 0.013) were associated with decreased risk of medication discontinuation.

Discussion and Conclusion

This investigation suggests that patient-generated content can inform the study of health-related behaviors. Given that approximately 50% of breast cancer patients do not complete a course of hormonal therapy as described, the identification of factors associated with medication discontinuation can facilitate real-time interventions to prevent early discontinuation.

Influence of patient and tumor characteristics on early therapy persistence with letrozole in postmenopausal women with early breast cancer: results of the prospective Evaluate-TM study with 3941 patients

Background

Patients' compliance and persistence with endocrine treatment has a significant effect on the prognosis in early breast cancer (EBC). The purpose of this analysis was to identify possible reasons for non-persistence, defined as premature cessation of therapy, on the basis of patient and tumor characteristics in individuals receiving adjuvant treatment with letrozole.

Patients and methods

The EvAluate-TM study is a prospective, multicenter, noninterventional study in which treatment with the aromatase inhibitor letrozole was evaluated in postmenopausal women with hormone receptor-positive EBC in the early therapy phase. Treatment persistence was evaluated at two pre-specified study visits after 6 and 12 months. As a measure of early therapy persistence the time from the start to the end of treatment (TTEOT) was analyzed. Cox regression analyses were carried out to identify patient characteristics and tumor characteristics predicting TTEOT.

Results

Out of the total population of 3941 patients with EBC, 540 (13.7%) events involving treatment cessation unrelated to disease progression were observed. This was due to drug-related toxicity in the majority of cases (73.5%). Persistence rates were 92.2%, 86.9%, and 86.3% after 6, 12, and 15 months, respectively. The main factors influencing premature treatment discontinuation were older age [hazard ratio (HR) 1.02/year], comorbidities (HR 1.06 per comorbidity), low body mass index, and lower tumor grade (HR 0.85 per grade unit).

Conclusion

These results support the view that older, multimorbid patients with low tumor grade and low body mass index are at the greatest risk for treatment discontinuation and might benefit from compliance and support programs.

Preexisting musculoskeletal burden and its development under letrozole treatment in early breast cancer patients

One of the most common adverse events (AEs) occurring during treatment with aromatase inhibitors (AIs) is musculoskeletal pain. The aim of our study was to analyze the influence of preexisting muscle/limb pain and joint pain on the development of AI-induced musculoskeletal AEs. Women eligible for upfront adjuvant endocrine therapy with letrozole were included in the PreFace study, a multicenter phase IV trial. During the first treatment year, they were asked to record musculoskeletal AEs monthly by answering questions regarding pain symptoms and rating the pain intensity on a numeric rating scale from 0 (no pain) to 10 (very strong pain). Pain values were compared using nonparametric statistical tests. Overall, 1,416 patients were evaluable. The average pain value over all time points in women with preexisting muscle/limb pain was 4.3 (median 4.3); in those without preexisting pain, it was 2.0 (median 1.7). In patients without preexisting muscle/limb pain, pain levels increased relatively strongly within the first 6 months (mean increase +0.9, p < 0.00001) in comparison with those with preexisting pain (mean increase +0.3, p < 0.001), resulting in a statistically significant difference (p < 0.00001) between the two groups. The development of joint pain was similar in the two groups. Women without preexisting muscle/limb pain or joint pain have the greatest increase in pain after the start of adjuvant AI therapy. Women with preexisting pain have significantly higher pain values. The main increase in pain values takes place during the first 6 months of treatment.

Oral Endocrine Therapy Nonadherence, Adverse Effects, Decisional Support, and Decisional Needs in Women With Breast Cancer

BACKGROUND

Oral endocrine therapy (OET) such as tamoxifen or aromatase inhibitors reduces recurrence and mortality for the 75% of breast cancer survivors (BCSs) with a diagnosis of estrogen receptor-positive breast cancer. Because many BCSs decide not take OET as recommended because of adverse effects, understanding BCSs' decisional supports and needs is foundational to supporting quality OET decision making about whether to adhere to OET.

OBJECTIVE

The aim of this study was to examine literature pertaining to OET nonadherence and adverse effects using the Ottawa Decision Support Framework categories of decisional supports and decisional needs because these factors potentially influence OET use.

METHODS

A systematic literature search was performed in PubMed and CINAHL using combined search terms "aromatase inhibitors and adherence" and "tamoxifen and adherence." Studies that did not meet criteria were excluded. Relevant data from 25 publications were extracted into tables and reviewed by 2 authors.

RESULTS

Findings identified the impact of adverse effects on OET nonadherence, an absence of decisional supports provided to or available for BCSs who are experiencing OET adverse effects, and the likelihood of unmet decisional needs related to OET.

CONCLUSIONS

Adverse effects contribute to BCSs decisions to stop OET, yet there has been little investigation of the process through which that occurs. This review serves as a call to action for providers to provide support to BCSs experiencing OET adverse effects and facing decisions related to nonadherence.

IMPLICATIONS FOR PRACTICE

Findings suggest BCSs prescribed OET have unmet decisional needs, and more decisional supports are needed for BCSs experiencing OET adverse effects.

Predictors of vasomotor symptoms among breast cancer survivors

PURPOSE

Vasomotor symptoms (VMS) are a common side effect of breast cancer treatment, yet modifiable factors that may predict VMS among breast cancer survivors are unknown.

METHODS

We estimated multivariable-adjusted odds ratios and 95% confidence intervals (aOR, 95% CI) for predictors of VMS among 3595 breast cancer survivors enrolled in the Life and Longevity after Cancer (LILAC) study, an ancillary study of the Women's Health Initiative (WHI).

RESULTS

VMS post-diagnosis were reported by 790 (22.0%) participants. Risk of VMS after diagnosis was positively associated with prior chemotherapy (aOR 1.80, 95% CI 1.21-2.68) and adjuvant hormone therapy (aOR 2.73, 95% CI 2.08-3.58), postmenopausal hormone therapy use (aOR 1.67, 95% CI 1.30-2.13), prior VMS (aOR 2.20, 95% CI 1.73-2.80), bilateral oophorectomy (aOR 1.77, 95% CI 1.37-2.27), and baseline antidepressant use (aOR 1.49, 1.06-2.09). VMS post-diagnosis were less likely among younger women (aOR 0.94, 95% CI 0.93-0.96), women younger at menopause (aOR 0.98, 95% CI 0.97-1.00), women with more time since diagnosis (aOR 0.92, 95% CI 0.90-0.94), and diabetics (aOR 0.45, 95% CI 0.21-0.95). Metabolic syndrome was not associated with post-diagnosis VMS (aOR 0.76, 95% CI 0.45-1.28).

CONCLUSIONS

VMS following breast cancer diagnosis was related to a number of modifiable factors, but was unrelated to metabolic syndrome.

IMPLICATIONS FOR CANCER SURVIVORS

Identification of factors that predispose women to VMS following a breast cancer diagnosis may allow clinicians to recognize and address VMS in the subset of women who are most likely to experience such symptoms.

Obesity and breast cancer - Role of estrogens and the molecular underpinnings of aromatase regulation in breast adipose tissue

One in eight women will develop breast cancer over their lifetime making it the most common female cancer. The cause of breast cancer is multifactorial and includes hormonal, genetic and environmental cues. Obesity is now an accepted risk factor for breast cancer in postmenopausal women, particularly for the hormone-dependent subtype of breast cancer. Obesity, which is characterized by an excess accumulation of body fat, is at the origin of chronic inflammation of white adipose tissue and is associated with dramatic changes in the biology of adipocytes leading to their dysfunction. Inflammatory factors found in the breast of obese women considerably impact estrogen signaling, mainly by driving changes in aromatase expression the enzyme responsible for estrogen production, and therefore promote tumor formation and progression. There is thus a strong link between adipose inflammation and estrogen biosynthesis and their signaling pathways converge in obese patients. This review describes how obesity-related factors can affect the risk of hormone-dependent breast cancer, highlighting the different molecular mechanisms and metabolic pathways involved in aromatase regulation, estrogen production and breast malignancy in the context of obesity.

Facilitating adherence to endocrine therapy in breast cancer: stability and predictive power of treatment expectations in a 2-year prospective study

PURPOSE

To identify modifiable factors predictive of long-term adherence to adjuvant endocrine therapy (AET).

METHODS

As part of a 2-year cohort study in primary care (n = 116), we investigated whether initial treatment expectations predict adherence at 24 months after controlling for demographic, medical, and psychosocial variables. Treatment expectations were measured as necessity-concern beliefs, expected side-effect severity, and expected coping with side effects. Their stability over time and differences of trajectories between the adherent and nonadherent group were examined.

RESULTS

Nonadherence at 24 months was 14.7% (n = 17). Side-effect severity at 3 months [OR 0.25, 95% CI (0.08, 0.81), p = 0.02] and necessity-concern beliefs [OR 2.03, 95% CI (1.11, 3.72), p = 0.02] were the sole predictors of adherence. Necessity-concern beliefs remained stable over 2 years, whereas expected side-effect severity (p = 0.01, η p2  = 0.07) and expected coping with side effects became less optimistic over time (p < 0.001, η p2  = 0.19), the latter particularly among nonadherers (p < 0.01, η p2  = 0.10).

CONCLUSIONS

Patients' initial necessity-concern beliefs about the AET and early severity of side effects affect long-term adherence. Expecting poor management of side effects may also facilitate nonadherence. We suggest that discussing benefits, addressing concerns of AET, and providing side-effect coping strategies could constitute a feasible and promising option to improve adherence in clinical practice.

Fatores associados à adesão e à persistência na hormonioterapia em mulheres com câncer de mama

RESUMO: Introdução: A hormonioterapia no câncer de mama é fundamental para a transição do tratamento ativo aos cuidados de sobrevivência, pois melhora significativamente os resultados de sobrevida em longo prazo, além de propiciar melhor qualidade de vida e reduzir os custos de hospitalização. Porém, para atingir resultados desejáveis, são importantes a adesão e a persistência no tratamento recomendado. Metodologia: Estudo de coorte retrospectivo com 182 mulheres em tratamento hormonal identificadas em unidade oncológica de alta complexidade da Região Sudeste do Brasil e acompanhadas até 2014. Foram realizadas análise bivariada, para investigar os fatores associados à adesão, e regressão multivariada de Cox, para identificar variáveis associadas à descontinuidade do tratamento ao longo do tempo. Resultados: A adesão geral foi de 85,2% e a persistência, de 45,4% após 5 anos. Não foi encontrada associação entre as variáveis independentes estudadas e a adesão. Mulheres com estadiamento avançado (hazard ratio - HR = 2,24; intervalo de confiança de 95% - IC95% 1,45 - 3,45), que não realizaram cirurgia (HR = 3,46; IC95% 2,00 - 5,97) e com 3 ou mais internações hospitalares (HR = 6,06; IC95% 2,53 - 14,54) exibiram maior risco de descontinuidade. Discussão: As variáveis associadas à persistência refletem a relação entre a maior gravidade da doença e a interrupção do tratamento hormonal adjuvante. Conclusão: Apesar da alta adesão, observa-se aumento progressivo do número de pacientes que não persistem no tratamento, devido a características relacionadas à gravidade da doença, contribuindo para uma resposta terapêutica inadequada.

Barriers and facilitators of adjuvant hormone therapy adherence and persistence in women with breast cancer: a systematic review

PURPOSE

Nonadherence to hormone therapy in breast cancer survivors is common and associated with increased risk of mortality. Consistent predictors of nonadherence and nonpersistence are yet to be identified, and little research has examined psychosocial factors that may be amenable to change through intervention. This review aimed to identify predictors of nonadherence and nonpersistence to hormone therapy in breast cancer survivors in order to inform development of an intervention to increase adherence rates.

METHODS

Studies published up to April 2016 were identified through MEDLINE, Embase, Web of Science, PsycINFO, CINAHL and gray literature. Studies published in English measuring associations between adherence or persistence and any predictor variables were included. Eligible studies were assessed for methodological quality, data were extracted and a narrative synthesis was conducted.

RESULTS

Sixty-one eligible articles were identified. Most studies focused on clinical and demographic factors with inconsistent results. Some evidence suggested that receiving specialist care and social support were related to increased persistence, younger age and increased number of hospitalizations were associated with nonadherence, and good patient-physician relationship and self-efficacy for taking medication were associated with better adherence. A small amount of evidence suggested that medication beliefs were associated with adherence, but more high-quality research is needed to confirm this.

CONCLUSION

Some psychosocial variables were associated with better adherence and persistence, but the results are currently tentative. Future high-quality research should be carried out to identify psychosocial determinants of nonadherence or nonpersistence that are modifiable through intervention.

Can demographic, clinical and treatment-related factors available at hormonal therapy initiation predict non-persistence in women with stage I-III breast cancer?

PURPOSE

To investigate whether demographic, clinical and treatment-related risk factors known at treatment initiation can be used to reliably predict future hormonal therapy non-persistence in women with breast cancer, and to inform intervention development.

METHODS

Women with stage I-III breast cancer diagnosed 2000-2012 and prescribed hormonal therapy were identified from the National Cancer Registry Ireland (NCRI) and linked to pharmacy claims data from Ireland's Primary Care Reimbursement Services (PCRS). Non-persistence was defined as a treatment gap of ≥180 days within 5 years of initiation. Seventeen demographic, clinical and treatment-related risk factors, identified from a systematic review, were abstracted from the NCRI-PCRS dataset. Multivariate binomial models were used to estimate relative risks (RR) and risk differences (RD) for associations between risk factors and non-persistence. Calibration and discriminative performance of the models were assessed. The analysis was repeated for early non-persistence (<1 year of initiation).

RESULTS

Within 5 years of treatment initiation 680 women (19.9%) were non-persistent. Women aged <50 years (adjusted RR 1.41, 95% CI 1.16-1.70) and those prescribed antidepressants (RR 1.22, 95% CI 1.04-1.45) had increased risk of non-persistence. Married women (RR 0.82 95% CI 0.71-0.94) and those with prior medication use (RR 0.62 95% CI 0.51-0.75) had reduced risk of non-persistence. The area under the receiver-operating characteristic (ROC) curve for non-persistence was 0.61. Findings were similar for early non-persistence.

CONCLUSION

The risk prediction model did not discriminate well between women at higher and lower risk of non-persistence at treatment initiation. Future studies should consider other factors, such as psychological characteristics and experience of side-effects.

Switching between endocrine therapies for primary breast cancer: Frequency and timing in Australian clinical practice

AIMS

To determine the frequency, timing and patterns of endocrine therapy switching in Australian practice for postmenopausal women with primary breast cancer.

METHODS

We identified postmenopausal women in a population-based cohort commencing endocrine therapy for invasive primary breast cancer between December 2005 and December 2008 (n = 645). Individual-level administrative health records and self-report data were used to determine women's demographic and clinical characteristics, including preexisting and newly-treated comorbidities, and switches in endocrine therapy. Time to therapy switching was calculated. Chi-square tests compared the characteristics of women who did and did not switch, and those switching within 2 years or after 2 years of commencing therapy.

RESULTS

Twenty-eight percent of women switched from their initial endocrine therapy, most commonly from tamoxifen to anastrozole, or the converse. A small number of anastrozole-to-exemestane and letrozole-to-exemestane switches were observed (n = 19). Most women (>80%) who switched therapies did not have newly-treated comorbidities. Few women (<5%) switched before completing 2 years of therapy, but these women were significantly more likely to have preexisting antidepressant use than women switching later (43% vs 23%, P = 0.048) and remained on the subsequent therapy for less time (6 months vs 2.7 years, P < 0.001).

CONCLUSIONS

Approximately one-quarter of postmenopausal women with primary breast cancer switched endocrine therapies. The findings suggest that the majority of switching in Australian practice was planned; occurring after 2-3 years of, not precipitated by comorbidity, and in a sequence supported by trial evidence. Early switching, however, was associated with preexisting depression and appeared to be a marker of poor persistence.

Oral Endocrine Therapy Nonadherence, Adverse Effects, Decisional Support, and Decisional Needs in Women With Breast Cancer

BACKGROUND

Oral endocrine therapy (OET) such as tamoxifen or aromatase inhibitors reduces recurrence and mortality for the 75% of breast cancer survivors (BCSs) with a diagnosis of estrogen receptor-positive breast cancer. Because many BCSs decide not take OET as recommended because of adverse effects, understanding BCSs' decisional supports and needs is foundational to supporting quality OET decision making about whether to adhere to OET.

OBJECTIVE

The aim of this study was to examine literature pertaining to OET nonadherence and adverse effects using the Ottawa Decision Support Framework categories of decisional supports and decisional needs because these factors potentially influence OET use.

METHODS

A systematic literature search was performed in PubMed and CINAHL using combined search terms "aromatase inhibitors and adherence" and "tamoxifen and adherence." Studies that did not meet criteria were excluded. Relevant data from 25 publications were extracted into tables and reviewed by 2 authors.

RESULTS

Findings identified the impact of adverse effects on OET nonadherence, an absence of decisional supports provided to or available for BCSs who are experiencing OET adverse effects, and the likelihood of unmet decisional needs related to OET.

CONCLUSIONS

Adverse effects contribute to BCSs decisions to stop OET, yet there has been little investigation of the process through which that occurs. This review serves as a call to action for providers to provide support to BCSs experiencing OET adverse effects and facing decisions related to nonadherence.

IMPLICATIONS FOR PRACTICE

Findings suggest BCSs prescribed OET have unmet decisional needs, and more decisional supports are needed for BCSs experiencing OET adverse effects.

Patient-Reported Outcomes and Early Discontinuation in Aromatase Inhibitor-Treated Postmenopausal Women With Early Stage Breast Cancer

In the prospective Exemestane and Letrozole Pharmacogenetics trial of adjuvant aromatase inhibitor (AI) therapy for early-stage breast cancer, worsening of multiple treatment-related symptoms during AI therapy predicted AI early discontinuation. If these findings are confirmed in independent trials, early detection of changes in PRO measures could be used clinically to target interventions in patients at high risk for early discontinuation.

Background.

Early discontinuation of aromatase inhibitors (AIs) is common and leads to poor outcomes but is challenging to predict. In the Exemestane and Letrozole Pharmacogenetics trial, a high rate of early discontinuation due to intolerance was observed. We hypothesized that early changes in patient-reported outcomes (PROs) predict AI discontinuation and that biochemical factors are associated with changes in PROs.

Patients and Methods.

Postmenopausal women with early-stage breast cancer enrolled in a prospective randomized trial of exemestane versus letrozole completed questionnaires at baseline and serially over 24 months to assess overall quality of life (EuroQOL Visual Analog Scale [VAS]); mood; and multiple symptoms, including a musculoskeletal symptom cluster. A joint mixed-effects/survival model was used to estimate the effect of the change in PROs on AI discontinuation. Associations between biochemical factors and change in PROs were examined.

Results.

A total of 490 patients were analyzed. Worsening of EuroQOL VAS and the musculoskeletal cluster were associated with the highest risk for early discontinuation (hazard ratio [HR], 2.77 [95% confidence interval (CI), 2.72–2.81; p = .015]; HR, 4.39 [95% CI, 2.40–8.02; p < .0001], respectively). Pharmacokinetics and estrogen metabolism were not consistently associated with change in PRO measures. No clinically significant differences in any PRO between AIs were observed.

Conclusion.

Changes in PROs early during AI therapy were associated with treatment discontinuation. Identification of these changes could be used to target interventions in patients at high risk for early discontinuation.

Implications for Practice:

Early changes in patient-reported outcomes (PROs) can predict nonpersistence to aromatase inhibitor therapy. If used in clinical practice, PROs might identify women at highest risk for early discontinuation and allow for interventions to improve tolerance before significant toxicities develop. Further research is needed to improve capturing PROs in routine clinical practice.

Hypothalamic orexin's role in exacerbated cutaneous vasodilation responses to an anxiogenic stimulus in a surgical menopause model

Distressing symptoms such as hot flashes and sleep disturbances affect over 70% of women approaching menopause for an average of 4-7 years, and recent large cohort studies have shown that anxiety and stress are strongly associated with more severe and persistent hot flashes and can induce hot flashes. Although high estrogen doses alleviate symptoms, extended use increases health risks, and current non-hormonal therapies are marginally better than placebo. The lack of effective non-hormonal treatments is largely due to the limited understanding of the mechanisms that underlie menopausal symptoms. One mechanistic pathway that has not been explored is the wake-promoting orexin neuropeptide system. Orexin is exclusively synthesized in the estrogen receptor rich perifornical hypothalamic region, and has an emerging role in anxiety and thermoregulation. In female rodents, estrogens tonically inhibit expression of orexin, and estrogen replacement normalizes severely elevated central orexin levels in postmenopausal women. Using an ovariectomy menopause model, we demonstrated that an anxiogenic compound elicited exacerbated hot flash-associated increases in tail skin temperature (TST, that is blocked with estrogen), and cellular responses in orexin neurons and efferent targets. Furthermore, systemic administration of centrally active, selective orexin 1 or 2 and dual receptor antagonists attenuated or blocked TST responses, respectively. This included the reformulated Suvorexant, which was recently FDA-approved for treating insomnia. Collectively, our data support the hypothesis that dramatic loss of estrogen tone during menopausal states leads to a hyperactive orexin system that contributes to symptoms such as anxiety, insomnia, and more severe hot flashes. Additionally, orexin receptor antagonists may represent a novel non-hormonal therapy for treating menopausal symptoms, with minimal side effects.

Dry eyes and AIs: If you don't ask you won't find out

OBJECTIVES

Our objective was to investigate the hypothesis that women on adjuvant aromatase inhibitors (AIs) for treatment of breast cancer have a higher prevalence of dry eye syndrome (DES) compared with controls.

MATERIALS AND METHODS

Exposure and control groups were recruited. A cross sectional questionnaire-based study was performed. Demographic data and medical histories were collected. The presence of dry eye syndrome was determined by the ocular surface disease index (OSDI). The Functional Assessment of Cancer Treatment - Endocrine Subscale (FACT-ES) was performed to investigate correlations with other side effects of AIs.

RESULTS

93 exposure group and 100 control group questionnaires were included. The groups were similar in all demographic variables. The prevalence of dry eye syndrome was 35% (exposure) and 18% (control) (p < 0.01, OR 2.5). AIs were the only factor associated with dry eyes. The OSDI score was negatively correlated with the total FACT-ES score and positively correlated with duration of treatment.

CONCLUSION

Our study is the first to use a validated questionnaire to assess for DES in this population. DES is significantly more prevalent in women on AIs compared with controls. This is a newly emerging, and easily treated side effect of AIs. Self-reporting of dry eye symptoms underestimates the prevalence of DES with AIs. We recommend routine screening of patients on AIs with the OSDI with the aim of improving patient quality of life and possibly adherence.

Racial differences in depressive symptoms and self-rated health among breast cancer survivors on aromatase inhibitor therapy

The goal of this survey-based study was to examine whether aromatase inhibitor (AI) therapy was associated with depressive symptoms and self-rated health among Black and White breast cancer survivors (N = 761). Results showed that among Black, but not White, breast cancer survivors current AI therapy was associated with a significant increase in the odds of both depressive symptoms (OR 3.59; 95% CI 1.01, 13.00) and poorer self-rated health (OR 3.16; 95% CI 1.06, 9.46). Presence of pain was significantly associated with increased odds of both outcomes among both groups. The findings underscore the importance of addressing not only physical but mental health among breast cancer survivors on AIs, especially those of Black race.

Depression as a predictor of adherence to adjuvant endocrine therapy (AET) in women with breast cancer: a systematic review and meta-analysis

The purpose of this meta-analysis was to analyze the available evidence concerning the effects of depression on non-adherence to adjuvant endocrine therapy (AET) in women with breast cancer. MEDLINE and PsycInfo databases from inception through May 1, 2015 were searched using terms related to AET adherence. Articles were reviewed and selected based on predetermined selection criteria, and effect sizes from included studies were extracted. Pooled effect estimates were obtained using random-effects meta-analyses. Of the 312 articles identified, 9 met the inclusion criteria. Overall, depression was significantly associated with non-adherence to AET (Cohen's d = 0.35, 95% CI 0.19-0.52). This effect was not significantly moderated by patient age (<65 vs ≥65 years), length of study follow-up (<18 months vs ≥18 months), or method of assessing adherence (objective vs self-report). However, within these subgroups, significant effects of depression were found only for younger patients (d = 0.46; 95% CI 0.19-0.72) and in studies of shorter duration (<18 months) (d = 0.49; 95% CI 0.22-0.76). These results suggest that AET adherence may be lower among women with greater depressive symptoms, and this effect may be exacerbated in younger women during the early phases (<18 months) of AET. Management of depressive symptoms in women with breast cancer may help in enhancing adherence to AET and improve cancer treatment outcomes.

From prescriptions to drug use periods - things to notice

BACKGROUND

Electronic prescription registers provide a vast data source for pharmacoepidemiological research. Prescriptions as such are not suitable for all research purposes; e.g., studying concurrent use of different drugs or adverse drug events during current use. For those purposes, data on dispensed prescriptions needs to be transformed to periods of drug use.

METHODS

We used 3,828,292 dispensed prescriptions claimed between 1 January 2002 and 31 December 2009 for 28,093 persons with Alzheimer's disease. Examples of drug use histories are presented to discuss different aspects that should be noticed when using register-based data consisting of drug purchases.

RESULTS

There is no simple method for correctly transforming dispensed prescriptions to periods of drug use that is usable for all drugs and drug users. Fixed assumptions of daily dose (in defined daily doses, tablets or other units) and fixed time windows should be used with caution and adjusted for different drug use patterns.

CONCLUSIONS

We recommend that when transforming prescription drug purchases to drug use periods personal dose, purchasing pattern and other behavioral differences between patients should be taken into account.