1. HRB Centre for Primary Care Research, RCSI, Dublin
Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn
Multigroup multilevel segmented regression models & prescribing variation within the Preferred Drugs Scheme in Ireland
Ron McDowell, Tom Fahey
HRB Centre for Primary Care Research, RCSI, Dublin
Is hospitalisation associated with the unintentional discontinuation of appropriate long-term medication in the GP record?

2. Overview The Preferred Drugs Scheme Objectives Change in level models
Data & methods
Results
Comments
Conclusions

3. Preferred Drugs Scheme
Ireland spends 50% per capita above the EU average on drugs/pharmaceuticals.
2014: €1.3 billion (12% of the Health Service Executive’s budget) spent on prescription medication.
2013: introduction of the “Preferred Drugs Scheme” by the Medications Management Programme. 10 medication groups to date including Proton Pump Inhibitors (PPI), heart medications, psychotropics.
Preferred drug chosen on grounds such as clinical efficacy, international guidelines and cost.

4. Objectives
To examine the impact of national guidelines on the prescribing of the preferred Proton Pump Inhibitor (PPI) [Lansoprazole] in a cohort of older adults in Ireland between 2011 and 2015, distinguishing between new and pre-existing patients.
To examine where the variation lies: between patients, practices or both?
Note: Ireland has high levels of sustained PPI prescribing

5. Change in level models Segmented Regression Model
Interrupted Time Series Model
Latent Growth Curve Model
Other data features e.g. groups, clusters to take account of
Preference sensitive care : more than 1 recognised treatment option

6. Data & methods Medication Reconciliation cohort: Jan 2011-Sept 2015
21,481 patients; 41 GP practices in Ireland
Adults aged 65+ years
Data aggregated to obtain the number of PPI and Lansoprazole prescriptions per patient per calendar quarter per practice
Logistic segmented regression model with random effects.
2 groups of interest: patients who received PPI between Jan 2011 –March 2013 & April 2013-Dec 2015 and those who only had them from April 2013 onwards.
Models fit using MLWin/runMLwin.

7. Results 3.1 million prescriptions: Jan 2011-Sept 2015.
5.1% (158,824) for one of 5 PPIs of which 24.2% (38,487) for the preferred drug, Lansoprazole. Most common: Omeprazole (31.4%).
89.2% (11,162) of the 14,242 patients who received at least one PPI prescription received scripts in at least two calendar quarters

8. Results

9. Results
Practices which prescribed Lansoprazole among pre-existing PPI patients after April 2013 tended to prescribe it in new patients (ρ=0.32, 95%CI (0.14,0.49))

10. Between practice/patient variation

11. Comments Limitations: no practice-level/prescriber variables
Models do not as yet include potentially time-varying patient-level covariates:-
age, gender, insurance status, polypharmacy, contact with practice prior to April 2013.
Change the definition for inclusion: 2 or 3 consecutive PPI prescriptions each within 30 days of each other. Results hold.
Results are in line with expectations- changes in prescribing patterns tend to be very gradual
Considerable variation exists between practices in the prescribing of preferred drugs in Ireland.
Largest variability at start of study and introduction of guidelines, less so regarding changes over time.

12. Conclusions
Appears to have been some changes in prescribing patterns of PPIs with introduction of the Preferred Drug Scheme among older adults
More marked among the patients starting PPIs after guidelines were introduced rather than pre-existing patients
Most of the variation is due to differences in patients rather than practices-yet to be explained.
Less variation in prescribing of Lansoprazole among newer patients.
Models can be refined and developed further to address more specific research questions and to take account of further features of the data.