Survival Outcomes in Older Women with Oestrogen-Receptor-Positive Early-Stage Breast Cancer: Primary Endocrine Therapy vs. Surgery by Comorbidity and Frailty Levels.

Primary endocrine therapy (PET) offers non-surgical treatment for older women with early-stage breast cancer who are unsuitable for surgery due to frailty or comorbidity. This research assessed all-cause and breast cancer-specific mortality of PET vs. surgery in older women (≥70 years) with oestrogen-receptor-positive early-stage breast cancer by frailty and comorbidity levels. This study used UK secondary data to analyse older female patients from 2000 to 2016. Patients were censored until 31 May 2019 and grouped by the Charlson comorbidity index (CCI) and hospital frailty risk score (HFRS). Cox regression models compared all-cause and breast cancer-specific mortality between PET and surgery within each group, adjusting for patient preferences and covariates. Sensitivity analyses accounted for competing risks. There were 23,109 patients included. The hazard ratio (HR) comparing PET to surgery for overall survival decreased significantly from 2.1 (95%CI: 2.0, 2.2) to 1.2 (95%CI: 1.1, 1.5) with increasing HFRS and from 2.1 (95%CI: 2.0, 2.2) to 1.4 (95%CI 1.2, 1.7) with rising CCI. However, there was no difference in BCSM for frail older women (HR: 1.2; 0.9, 1.9). There were no differences in competing risk profiles between other causes of death and breast cancer-specific mortality with PET versus surgery, with a subdistribution hazard ratio of 1.1 (0.9, 1.4) for high-level HFRS (p = 0.261) and CCI (p = 0.093). Given limited survival gains from surgery for older patients, PET shows potential as an effective option for frail older women with early-stage breast cancer. Despite surgery outperforming PET, surgery loses its edge as frailty increases, with negligible differences in the very frail.

Risk of serious infection and infection mortality in patients with psoriasis: A nationwide cohort study using the Taiwan National Health Insurance claims database.

BACKGROUND: The risks of serious infections that lead to hospitalization and mortality in patients with psoriasis in Asia have not been comprehensively studied. OBJECTIVES: We examined the incidence of serious infection and infection mortality in patients with psoriasis. METHODS: This population-based retrospective cohort study used the Taiwan National Health Insurance claims database from 2000 to 2017. Adult patients with psoriasis were identified by a relevant International Classification of Diseases (ICD) code and matched to six comparators without psoriasis on age and sex. Psoriasis patients were categorized as having moderate-to-severe disease once exposed to systemic therapies, phototherapy or biologic therapies. The incidence of serious infection and infection mortality were identified by ICD codes from inpatient hospitalization and death registration. Cox proportional hazard models were used to compare the risk, and the results were adjusted for covariates and presented as adjusted hazard ratios (aHR) and 95% confidence interval (95% CI). RESULTS: Overall, 185,434 psoriasis patients and 1,112,581 comparators were included. A higher rate of serious infection (aHR: 1.21, 95% CI: 1.19-1.22) was found in patients with psoriasis compared to matched comparators without psoriasis, and the risk was enhanced when patients had moderate-to-severe psoriasis (aHR: 1.30, 95% CI: 1.27-1.34). Specifically, there was an increased risk of serious infection due to respiratory infections (aHR: 1.11, 95% CI: 1.09-1.13), skin/soft-tissue infections (aHR: 1.57, 95% CI: 1.52-1.62), sepsis (aHR: 1.23, 95% CI: 1.19-1.27), urinary tract infections (aHR: 1.11, 95% CI: 1.08-1.14), hepatitis B (aHR: 1.18, 95% CI: 1.06-1.30) and hepatitis C (aHR: 1.49, 95% CI: 1.32-1.69). Furthermore, psoriasis patients were associated with a higher risk of infection-related mortality (aHR: 1.15, 95% CI: 1.11-1.18) compared to matched comparators. CONCLUSION: Patients with psoriasis had a higher risk of serious infection and infection mortality, which was enhanced by moderate-to-severe psoriasis. Practitioners should be aware of the increased risk in patients with psoriasis, but it should not be a barrier to offering effective treatment.

Longitudinal Trajectory of Opioid Prescribing and its Associated Serious Adverse Events: A Population-Wide Cohort Study in Taiwan.

Chronic opioid prescribing (COP) for noncancer pain is highly restricted in Taiwan, but tramadol is not listed in the regulation on chronic prescribing. This study investigated the trajectories of COP in noncancer pain when considering tramadol in Taiwan and identified the risk of serious adverse events. This population-wide longitudinal cohort study used the Taiwan National Health Insurance claims records from 2001 to 2016. Adults prescribed opioids (including tramadol) and without cancer were selected. Patients who received COP (opioid supply days for 28 days or continuous opioid supply for 14 days) in the first patient quarter were included, and serious adverse events were identified. Group-based trajectory models were applied to identify patients with a similar trajectory of quarterly COP. The Cox proportional hazard model was applied to assess the association between adverse events and patients' trajectories. Of the 2,360,358 noncancer opioid users, 476,934 (20.2%) received COP in the first quarter. Four groups of COP trajectory were identified, and 59,310 (12.8%) patients received COP quarterly over 2 years. Patients categorized into the trajectory of long-term COP had a significantly higher crude incidence rate of cardiovascular death, seizure, and hypoglycemia. Still, there is no newly developed opioid use disorder. There was a substantial underestimate in COP in Taiwan when tramadol was not considered. Notably, 10% of them could receive COP for over 2 years. The result raises concern about unmet pain management needs and the limited accessibility of alternative treatments for noncancer pain.

Fertility Trends and Adverse Pregnancy Outcomes in Female Patients With Psoriasis in the UK.

Importance: Evidence regarding fertility trends and obstetric outcomes among patients with psoriasis is limited by studies of small sample sizes, noninclusion of comparators, and the lack of accurate pregnancy records. Objective: To investigate fertility rates and obstetric outcomes of pregnancies in female patients with psoriasis compared with age- and general practice-matched comparators without psoriasis. Design, Setting, and Participants: This population-based cohort study used data from 887 primary care practices that contributed to the UK Clinical Practice Research Datalink GOLD database between 1998 and 2019, linked to a pregnancy register and Hospital Episode Statistics. There were 6 223 298 patients of common childbearing ages (15-44 years), and 63 681 patients with psoriasis had at least 1 year of follow-up data prior to the diagnosis of psoriasis. For each patient with psoriasis, 5 patients were matched by age from the same general practice. The median follow-up duration was 4.1 years. Data analysis was performed in 2021. Exposures: Patients with psoriasis were identified using clinical diagnostic codes from consultations. Main Outcomes and Measures: Fertility rates were calculated as the number of pregnancies per 100 patient-years. The outcomes of each pregnancy recorded in the pregnancy register or Hospital Episode Statistics were screened to identify obstetric outcomes. A negative binomial model was used to examine the association between psoriasis and the fertility rate. Logistic regression was applied to compare the association between psoriasis and obstetric outcomes. Results: A total of 63 681 patients with psoriasis and 318 405 matched comparators were included in the analysis (median [IQR] age, 30 [22-37] years). Lower fertility rates (rate ratio, 0.75; 95% CI, 0.69-0.83) were found in patients with moderate to severe psoriasis. Compared with matched comparators without psoriasis, pregnancies in patients with psoriasis had a higher risk of loss (odds ratio, 1.06; 95% CI, 1.03-1.10); however, there was no increase in the risks of antenatal hemorrhage, preeclampsia, or gestational diabetes. Conclusion and Relevance: In this cohort study, patients with moderate to severe psoriasis had a lower fertility rate, and the risk of pregnancy loss was higher than in matched comparators without psoriasis. Future research should identify the mechanism of increased risk of pregnancy loss among patients with psoriasis.

Feasibility and validity of using healthcare databases to conduct cross-national comparative studies of opioid use, its determinants and consequences.

PURPOSE: A cross-national comparative (CNC) study about opioid utilization would allow the identification of strategies to improve pain management and mitigate risk. However, little is known about the accessibility and validity of information in healthcare databases internationally. This study aimed to identify the feasibility of using healthcare databases to conduct a CNC study of opioid utilization and its associated consequences. METHODS: A cross-sectional survey was launched in March 2018, including experts interested in CNC studies comparing opioid utilization by purposeful sampling. An electronic survey was used to collect database characteristics, medicine information, and linkage information of each aggregate-level dataset (AD) and individual patient-level dataset (IPD). RESULTS: Overall, participants from 21 geographical regions reported 18 ADs and 19 IPDs. Information on dispensed medications is available from 17 ADs and 17 IPDs. Of the 16 ADs that include primary care settings, only 9 ADs can obtain information from secondary care settings. Fourteen IPDs included patients' characteristics or could be retrieved from linkage databases. Although most ADs are publicly accessible (n = 13), only five IPDs can be accessed without extra cost. CONCLUSION: Most ADs could be used to report opioid utilization in a primary care setting. IPDs with linkage databases should be applied to identify potential determinants, clinical outcomes, and policy impact. Data access restrictions and governance policies across jurisdictions can be challenging for timely analysis and require further collaboration.

Incidence, Prevalence, and Mortality of People with Psoriasis and Psoriatic Arthritis in Taiwan: A Nationwide Cohort Study.

There is a recognized need to better understand changes in the epidemiology of psoriasis and psoriatic arthritis (PsA) over time in Asia. Using the Taiwan National Health Insurance claim records this population-based study examined changes in the prevalence, incidence, and mortality rates in patients with psoriasis or psoriatic arthritis in Taiwan over 12 years. Patients with ≥1 diagnosis code for psoriasis or psoriatic arthritis, recorded either by dermatologists or rheumatologists, were identified. Annual age- and sex-standardized prevalence and incidence rates were calculated using the Taiwan general population as reference. To investigate mortality, each patient in the incident cohort was matched to 10 comparators from the general population by sex and age (at diagnosis). The risk of mortality between study cohorts and comparators was analysed by Cox proportional hazard regression. The prevalence of psoriasis (0.18-0.86%) and psoriatic arthritis (0.01-0.08%) increased steadily between 2006 and 2017. The incidence rates, however, remained stable (psoriasis: 62-65 per 100,000 person-years; psoriatic arthritis: 6-5 per 100,000 person-years). The risk of all-cause mortality for patients with psoriasis (hazard ratio 1.16; 95% confidence interval: 1.13-1.19) was higher than the general population, despite a decreasing trend over time in the all-cause mortality rates for both groups. The steady increase in the prevalence of psoriasis despite stable incidence rates suggests that improvements in life expectancy may be the key determinant of this increase.

Regional variation in longitudinal trajectories of primary care opioids prescribing across Health Boards in Scotland: a population-based study.

BACKGROUND: This study aims to describe the longitudinal trajectory of opioid prescribing at the practice level and assess associated factors, including Health Boards and socioeconomic status. RESEARCH DESIGN AND METHODS: This drug utilization research used practice-level dispensing data from 2016 to 2018. Practice-level prescription opioids dispensed were quantified by the defined daily doses (DDDs) per 1000 registrants. Group-based trajectory models were used to identify groups of practices with similar trajectories based on the difference in monthly opioid utilization. Characteristics of registrants were associated with the trajectory by a conditional logistic regression and the prescription opioids dispensed by a random-effect regression model. RESULTS: Of the 798 practices, 29.5% increased opioid prescription by an additional 100 DDDs/1000 registrants/month during 2017 and 2018. Practice in southwest Scotland tended to be categorized into the group with increasing opioid utilization. Deprived socioeconomic status was associated with increasing opioid utilization (odds ratio: 2.2; 95% confidence interval: 1.5, 3.2) or higher annual opioid utilization (coefficient: 358.2; 95% confidence interval: 327.6, 388.8). CONCLUSIONS: Increasing opioid utilization over time was related to deprived socioeconomic status associated with chronic pain conditions and inequality in pain services. Further strategies to balance inequality are needed, which needs further investigation.

Association between opioid-related deaths and persistent opioid prescribing in primary care in England: A nested case-control study.

AIM: This study aimed to evaluate the association between opioid-related deaths and persistent opioid utilisation in the United Kingdom (UK). METHODS: This nested case-control study used the UK Clinical Practice Research Datalink, linking the Office for National Statistics death registration. Adult opioid users with recorded opioid-related death between 2000 and 2015 were included and matched to four opioid users (controls) based on a disease risk score. Persistent opioid utilisation (opioid prescriptions ≥3 quarters/year and oral morphine equivalent dose ≥4500 mg/year) and psychotropic prescriptions were identified annually during the three patient-years before the date of opioid-related death. Conditional logistic regression was used to assess the association between persistent opioid utilisation and opioid-related death, and the results were reported as adjusted odds ratios (aOR) and 95% confidence intervals (95% CI). RESULTS: Of the 902 149 opioid users, 230 opioid-related deaths (cases) and 920 controls were identified. Persistent opioid utilisation was significantly associated with an increased risk of opioid-related deaths (aOR 1.9, 95% CI 1.2, 2.9) when persistent opioid utilisation was defined by both annual dose and number of quarters. Concurrent prescription of opioids and tricyclic antidepressants (aOR 2.0, 95% CI 1.2, 3.5) or higher dose of benzodiazepine (aOR 6.5, 95% CI 4.0, 10.4) or gabapentinoids (aOR 6.2, 95% CI 2.9, 13.5) were associated with opioid-related death. CONCLUSION: Persistent opioid prescribing and concurrent prescribing of psychotropics were associated with a higher risk of opioid-related death and should be avoided in clinical practice. An evidence-based indicator to monitor the safety of prescribed opioids during opioid deprescribing is needed.

Association between opioid-related deaths and prescribed opioid dose and psychotropic medicines in England: a case-crossover study.

BACKGROUND: Opioid-overdose deaths are associated with poisoning with prescription and illicit opioids in the USA. In contrast, opioid-related deaths (ORDs) in the UK often involve drugs and substances of misuse, and may not be associated with a high dose of prescribed opioids. This study aimed to investigate the association between prescribed opioid dose and ORDs in UK primary care. METHODS: This case-crossover study used the Clinical Practice Research Datalink and death registration between 2000 and 2015 to identify ORDs. Daily oral morphine equivalent (OMEQ) dose was measured within a 90 day focal window before ORD and three earlier reference windows. Conditional logistic regression models assessed the adjusted odds ratio (aOR) and 95% confidence interval (95% CI) comparing daily OMEQ dose greater than 120 mg in the focal window against the reference windows. RESULTS: Of the 232 ORDs, 62 (26.7%) were not prescribed opioids in the year before death. Of the remaining 170 cases, 50 (29.4%) were never prescribed a daily OMEQ dose greater than 50 mg. Daily OMEQ doses over 120 mg (aOR 2.20; 95% CI: 1.06-4.56), co-prescribing gabapentinoids (aOR 2.32; 95% CI: 1.01-5.33), or some antidepressants (aOR 3.03; 95% CI: 1.02-9.04) significantly increased the risk of ORD. CONCLUSIONS: Daily OMEQ dose greater than 120 mg and the concomitant use of psychotropic medicines were related to ORDs in the UK. Prescribers should cautiously avoid prescribing opioids with a daily OMEQ dose greater than 120 mg day-1 and the combination of opioids and gabapentinoids, even with low opioid doses.

Investigating the prescribing trajectory and geographical drug utilisation patterns of gabapentinoids in primary care in England: An ecological study.

AIMS: This study aimed to investigate the prescribing trajectory, geographical variation and population factors, including socioeconomic status (SES), related to prescribing gabapentinoids in primary care in England. METHODS: This ecological study applied practice-level dispensing data and statistics from the UK National Health Service Digital and Office for National Statistics from 2013 to 2019. The prescribing of gabapentinoids (in defined daily doses [DDDs]/1000 people) was measured annually and quarterly. General practices were categorised according to the quarterly prescribing in a group-based trajectory model. The one-year prescribing in 2018/19 was associated with practice-level covariates in a mixed-effects multilevel regression, adjusted for the cluster-effects of Clinical Commissioning Groups (CCGs) and mapped geographically. RESULTS: The annual national prescription rate increased by 70% from 2800 to 4773 DDDs/1000 people in the time period 2013/14 to 2018/19. General practices were stratified into six trajectory groups. Practices with the highest level and the greatest increase in prescribing (n = 789; 9.8%) are mainly located in the north of England and along the east and south coastline. Socioeconomic status, demographic characteristics and relevant disease conditions were significantly associated with the prescribing. For every decrease in the Index of Multiple Deprivation decile (becoming less affluent), prescribing of gabapentinoids increased significantly by 203 (95% CI: 183-222) DDDs/1000 registrants. CONCLUSIONS: Gabapentinoid prescribing trajectories varied across geographical regions and are associated with socioeconomic status, CCG locality (geography) and other population characteristics. These factors should be considered in future studies investigating the determinants of gabapentinoid prescribing and the risk of harms associated with gabapentinoids.

Increasing tramadol utilisation under strict regulatory control of opioid prescribing - A cross-sectional study in Taiwan from 2002 through 2016.

BACKGROUND/PURPOSE: Prescribing of opioids to patients with non-cancer pain is strictly regulated in Taiwan, but tramadol is not included in the regulation on chronic opioid prescribing. This study aims to identify the utilization trend of prescribing tramadol and other opioid analgesics and investigate the influence of government regulation on opioid prescribing in Taiwan. METHODS: This cross-sectional study used the Taiwan National Health Insurance claims database and the cancer registry from 2001 through 2016. The annual number of adult opioid users, opioid utilization (Defined Daily Doses [DDDs]/1000 registrants) and the number of supply days were enumerated for each calendar year and stratified by cancer or non-cancer patients. Descriptive statistics were used to report the trends in utilization for each calendar year. RESULTS: The regulation strictly limited persistent use of opioids for patients with non-cancer pain, of which only a small proportion of fentanyl (20%) and morphine (<2%) users were prescribed with an annual number of supply days greater than 28 days. The annual utilization of morphine (6.4-53.5 vs. 1.1 to 9.6 DDD/1000 registrants) and fentanyl (8.3-37.0 vs. 0.16 to 1.8 DDD/1000 registrants) to patients with cancer was consistently higher than patients without cancer. In contrast to morphine and fentanyl, the utilization of tramadol prescribed to patients without cancer increased 92.2-fold (3.7-341.2 DDD/1000 registrants) from 2002 to 2016. CONCLUSION: The regulation in Taiwan limited the prescribing of selective opioids for patients with non-cancer pain and the substitution of tramadol for other opioids may have safety implications.

Prescription opioids: Regional variation and socioeconomic status - evidence from primary care in England.

BACKGROUND: This study aimed to quantify opioid prescriptions dispensed from primary care practices throughout England and investigate its association with socioeconomic status (SES). METHODS: This cross-sectional study used publicly available data in 2015, including practice-level dispensing data and characteristics of registrants from the United Kingdom (UK) National Health Service Digital, and Index of Multiple Deprivation (IMD) data from Department of Communities and Local Government. Practices in England which issued opioid prescriptions that could be assigned a defined daily dose (DDD) in the claim-based dispensing database were included. The total amount of opioid prescriptions dispensed (DDD/1000 registrants/day) was calculated for each practice. The association between dispensed opioid prescriptions and IMD was analyzed by multi-level regression and adjusted for registrants' characteristics and the clustered effect of Clinical Commissioning Groups. Subgroup analysis was conducted for practices in London, Birmingham, Manchester and Newcastle. RESULTS: Of the 7856 included practices in England, the median and interquartile range (IQR) of prescription opioids dispensed was 36.9 (IQR: 23.1, 52.5) DDD/1000 registrants/day. The median opioid utilization (DDD/1000 registrants/day) amongst practices varied between Manchester (53.1; IQR: 36.8, 71.4), Newcastle (48.9; IQR: 38.8, 60.1), Birmingham (35.3; IQR: 23.1, 49.4) and London (13.9; IQR: 8.1, 18.8). Lower SES, increased prevalence of patients aged more than 65 years, female gender, smoking, obesity and depression were significantly associated with increased opioid prescriptions. For every decrease in IMD decile (lower SES), there was a significant increase of opioid utilization by 1.0 (95% confidence interval: 0.89, 1.2, P < 0.001) DDD/1000 registrants/day. CONCLUSION: There was substantial variation in opioid prescriptions among practices from Northern and Eastern England to Southern England. A significant association between increased opioid prescriptions and greater deprivation at a population level was observed. Further longitudinal studies using individual patient data are needed to validate this association and identify the potential mechanisms.

A 15-year overview of increasing tramadol utilisation and associated mortality and the impact of tramadol classification in the United Kingdom.

PURPOSE: This study aimed to develop hypotheses to explain the increasing tramadol utilisation, evaluate the impact of tramadol classification, and explore the trend between tramadol utilisation and related deaths in the United Kingdom. METHODS: This cross-sectional study used individual patient data, the Clinical Practice Research Datalink from 1993 to 2015, to calculate monthly defined daily dose (DDD)/1000 registrants, monthly prevalence and incidence of tramadol users, annual supply days, and mean daily dose of tramadol. Aggregated-level national statistics and reimbursement data from 2004 to 2015 were also used to quantify annual and monthly tramadol DDD/1000 inhabitants and rate of tramadol-related deaths in England and Wales. Interrupted time-series analysis was used to evaluate the impact of tramadol classification in June 2014. RESULTS: Prevalence of tramadol users increased from 23 to 97.6/10 000 registrants from 2000 to 2015. Both annual dose and annual supply days of existing tramadol users were higher than new users. Level and trend of monthly utilisation (ß2 : -12.9, ß3 : -1.6) and prevalence of tramadol users (ß2 : -6.4, ß3 : -0.37) significantly reduced after classification. Both annual tramadol utilisation and rate of tramadol-related deaths increased before tramadol classification and decreased thereafter. CONCLUSIONS: Increasing tramadol utilisation was influenced by the increase in prevalence and incidence of tramadol users, mean daily dose, and day of supply. Prevalence of tramadol users, tramadol utilisation, and reported deaths declined after tramadol classification. Future studies need to evaluate the influencing factors to ensure the safety of long-term tramadol use.

Disease acceptance and adherence to imatinib in Taiwanese chronic myeloid leukaemia outpatients.

BACKGROUND: The launch of imatinib has turned chronic myeloid leukaemia (CML) into a chronic illness due to the dramatic improvement in survival. Several recent studies have demonstrated that poor adherence to imatinib may hamper the therapeutic outcomes and result in increased medical expenditures, whilst research on exploring the reasons for non-adherence to imatinib is still limited. OBJECTIVE: This study aimed to explore the experience of patients as they journey through their CML treatments and associated imatinib utilisation in order to understand the perceptions, attitudes and concerns that may influence adherence to imatinib treatment. SETTING: This study was conducted at oncology outpatient clinics in a medical centre in southern Taiwan. METHODS: CML patients who regularly attended the oncology outpatient clinics to receive imatinib treatment from October 2011 to March 2012 were invited to participate in the study. Semi-structured face-to-face interviews were used to explore patients' experiences and views of their treatment, their current CML status and CML-related health conditions, their concerns about imatinib treatment and imatinib-taking behaviours. Patient interviews were recorded, transcribed verbatim and thematically analysed using the constant comparison approach. MAIN OUTCOME MEASURE: Themes related to patients' views of the disease and health conditions, worries and concerns influencing imatinib utilisation behaviours are reported. RESULTS: Forty-two CML patients participated in the interviews. The emerging themes included: acceptance of current disease and health status, misconceptions about disease progression, factors associated with adherence to imatinib, concerns and management of adverse drug effects. Participants regarded CML as a chronic disease but had misconceptions about disease progression, therapeutic monitoring, resistance to imatinib and symptoms of side effects. Participants were generally adherent to imatinib and favoured long-term prescriptions to avoid regular outpatient visits for medication refills. Experiencing adverse effect was the main reason influencing adherence and led to polypharmacy. Most participants altered medicine-taking behaviours to maintain long-term use of imatinib. CONCLUSION: Taiwanese CML patients are adherent to imatinib but report changing their medication-taking behaviour due to adverse drug effects and associated polypharmacy. Patients' misconceptions of the disease and medication suggests that it is necessary to improve communication between patients and healthcare professionals. Routinely providing updated information as part of the patient counselling process should be considered as a means of improving this communication.

Imatinib adherence associated clinical outcomes of chronic myeloid leukaemia treatment in Taiwan.

BACKGROUND: Since the launch of imatinib, chronic myeloid leukaemia has become a chronic condition requiring costly long-term treatment. Emerging evidence from several short-term studies has raised concerns on the detrimental clinical outcomes and waste of resources associated with poor adherence to imatinib. OBJECTIVE: This study aims to evaluate the effects of long-term imatinib adherence on clinical treatment responses and mortality. SETTING: This retrospective cohort study was conducted in a medical centre in southern Taiwan. METHOD: Chronic myeloid leukaemia patients who were prescribed for more than 1 month of imatinib were identified and their medical charts were reviewed from the first date of imatinib prescription to the last date of medical record or upon patients' death. Patients' basic characteristics, imatinib prescriptions, results of laboratory tests, episodes of imatinib-related side effects and mortality rate were recorded. MAIN OUTCOME MEASURE: Participants' basic characteristics, medication possession ratio and their mortality rate; the association between the medication possession ratio and treatment responses. RESULTS: Of the 119 included patients, the mean follow-up time was 3.9 ± 2.9 patient-years and the mean medication possession ratio was 89.7 %. At the 18th month of imatinib treatment, 67.2, 54.3 and 34.5 % patients achieved complete cytogenetic, major molecular and complete molecular responses, respectively. There was a significant difference in the 4-year survival rate between the adherence (n = 87) and non-adherence (n = 32) groups (91 vs. 72 %; p = 0.0076). Logistic regression analysis revealed that imatinib adherence was the only factor that significantly influenced the 18th month complete cytogenetic response [odds ratio (OR) 11.6; 95 % confidence interval (CI) 1.7, 114.7; p = 0.0131] and major molecular response (OR 5.1; 95 % CI 1.1, 26.8; p = 0.0351). Cox regression analysis demonstrated that a medication possession ratio greater than 90 % significantly reduced the mortality risk (hazard ratio 0.1; 95 % CI 0.01, 0.60; p = 0.0118). CONCLUSION: Chronic myeloid leukaemia patients' long-term adherence to imatinib is significantly associated with the 18th month treatment responses including the cytogenetic response, molecular response and the long-term survival rate in clinical practice.