Dapagliflozin in Type 2 Diabetes Patients, a Retrospective Cohort Study From Turkey

Background/Rationale:

Objectives and Hypotheses: To describe characteristics of patients with type 2 diabetes (T2D) prescribed dapagliflozin in routine internal medicine and endocrinology outpatient clinical care in Turkey; to describe changes in HbA1c(%), weight(kg), BMI(kg/m\^2) and blood pressure (BP)(mmHg) in these patients; and the discontinuation rates of dapagliflozin in the first 6 months of treatment.

Methods:

Study design: a retrospective observational cohort study. Data Source(s): Patient medical records of 81 different centres. Study Population: patients with a diagnosis of T2D, a first prescription for dapagliflozin, between July 2016 and Aug 2017 and who have been registered in the participating centre at least 6 months prior to first prescription of dapagliflozin.

Study variables: patient characteristics: age, gender, smoking status, co-morbidities, duration of diabetes, prescribed medicines, HbA1c(%), weight(kg), body mass index (BMI)(kg/m\^2) and blood pressure (BP)(mmHg).

Outcome(s): description of patient characteristics, HbA1c(%), weight(kg), BMI(kg/m\^2) and BP(mmHg) at baseline and during use of dapagliflozin at first visit (2,3 or 4 months) and second visit (5 or 6 months).

Sample Size Estimations:1500 patients Statistical Analysis: the baseline characteristics and follow up variables will be described using frequency and percentage distributions for categorical variables. Continuous and count variables will be described using mean (± standard deviation), median (quartiles) and 95% confidence intervals. Proportion of patients falling above/below certain weight(kg)/BMI(kg/m\^2), HbA1c(%) and BP(mmHg) thresholds will be derived. HbA1c(%), weight(kg), BMI(kg/m\^2) and BP(mmHg) will be described at baseline and during use of dapagliflozin. Over all questionnaire response rate and rate of response to reasons for prescribing dapagliflozin will be described.

Limitations: Variation in timing and completeness of clinical measures. The patient medical records are not collected for research purposes and the diagnostic and procedure coding on such data may be recorded incorrectly or not recorded at all, thereby potentially introducing measurement error with respect to code-based variables. The centres participating in the study, record that a prescription was issued, but not whether it was dispensed from the pharmacy.

This study is a descriptive retrospective observational cohort study using data from Turkish patient medical records from 81 different internal medicine and/or endocrinology clinics across the whole country.

The study cohort will include T2D patients who received at least one prescription for dapagliflozin for the first time between July 2016 and Aug 2017 and who have been registered in that centre for at least 6 months prior to the first dapagliflozin prescription.

The selection of sites and investigators will be made with an aim to achieve representativeness of the way dapagliflozin treated T2D patients are managed across Turkey. The National Coordinator will provide advice regarding the proportion of the different types of centres (Internal medicine, endocrinology clinics, different types of hospitals, geographical distribution) and investigators (different types of specialists) involved in dapagliflozin treated T2D patient management. The National Coordinator will also provide insight on the national situation regarding dapagliflozin medication prescription (reimbursement, public or private insurance). All this information will be used to select sites and investigators for the study, resembling as closely as possible, the real-world situation.

Sites will also be evaluated for existence and use of electronic medical records as part of feasibility. Data quality of sites will be assessed before initiation visit. The study centre database should provide at least 20 patients to the study. In case the study centre, can provide more than 20 patients, then patients will be selected randomly by the Contract Research Organization. Contract Research Organization will also record total number of eligible patients, their age and sex details before performing randomization. The randomization process will be performed at the study site after initiation visit by Contract Research Organization. The investigator of the centre will enter only selected patients to study Case Report Form. The Contract Research Organization will also perform 100% source document verification following completion of Case Report Forms by the investigator. All centres will be evaluated by Contract Research Organization at initiation visit in terms of data quality (Baseline, first visit and second visit data of eligible patients)

The date of the first prescription for dapagliflozin in patient medical records is the index date. Patients will be followed from the index date until the earliest of transfer out date, death date or end date of patient records (last date of data collection). Required data mentioned in baseline characteristics (section 5.1) will be recorded at index date, first visit (2 or 3 or 4 months after index date) and second visit (5 or 6 months after index date) of treatment (section 5.2).

Dataset quality will be assessed by Contract Research Organization at initiation visit. Site investigator is responsible for entering data to Case Report Forms. Paper based Case Report Form system will be used for this study. Datasets can differ for each hospital and patient's records can be electronic and/or printed. The investigator will collect all necessary data for each patient retrospectively from the most reliable data source in the clinic. All collected data will be verified by the Contract Research Organization.

Eligibility Criteria:
Inclusion Criteria:

* Age ≥18 and ≤75 years at index date.
* First prescription for dapagliflozin between July 2016 and Aug 2017
* Minimum 6 months of registration in the centres at the index date
* Established Type 2 diabetes prior to the index date

Exclusion Criteria:

* Patients with Type 1 diabetes
* Patients with gestational diabetes
* Being included in another interventional clinical trial at between index date and enrollment date
* Estimated Glomerular Filtration Rate \< 30 ml/min