Impact of a change of bronchodilator medications in a hospital drug formulary on intra- and out-of-hospital drug prescriptions: interrupted time series design with comparison group

Abstract

Background Hospital drug formularies are reduced lists of drugs designed to optimise inpatient care. Adherence to the drugs included in such formularies is not always 100% but is generally very high. Little research has targeted the impact of a change in these formularies on outpatient drug prescriptions. This study therefore sought to evaluate the impact of a change affecting bronchodilator medications in a hospital drug formulary on intra- and out-of-hospital drug prescriptions in a region in north-western Spain. Two new drugs belonging to this same class were brought onto the out-of-hospital market, overlapping with the intervention. Methods We used a natural before-after quasi-experimental design with control group based on monthly data. The intervention evaluated was the modification of a hospital drug formulary, which involved withdrawing salmeterol/fluticasone in order to retain formoterol/budesonide as the sole inhaled corticosteroid and long-acting beta-agonist (ICS/LABA). Using official data sources, we extracted the following dependent variables: defined daily doses (DDD) per 1000 inhabitants per day, DDD per 100 bed-days, and cost per DDD. Results Intra-hospital use showed a 173.2% rise (95% CI 47.3–299.0%) in the medication retained in the formulary, formoterol/budesonide, and a 94.9% drop (95% CI 77.9–111.9%) in the medication withdrawn from the formulary, salmeterol/fluticasone. This intervention led to an immediate reduction of 75.9% (95% CI 82.8–68.9%) in the intra-hospital cost per DDD of ICS/LABA. No significant changes were observed in out-of-hospital use. Conclusions Although this intervention was cost-effective in the intra-hospital setting, the out-of-hospital impact of a change in the drug formulary cannot be generalised to all types of medications and situations.

Prescription of anxiolytics, sedatives, hypnotics and antidepressants in outpatient, universal care during the COVID-19 pandemic in Portugal: a nationwide, interrupted time-series approach

“…An ITS analysis model based on a segmented regression approach 27–29 was designed to analyse the differences between the monthly prescribed DDDs of anxiolytics, sedatives, and hypnotics and antidepressants. A segmented linear regression analysis model 30 was designed to analyse the differences observed between March 2020 and March 2021, in terms of prescribed drugs. For statistical analysis purposes, we constructed a segmented regression model of the ITS for each outcome analysed: monthly prescribed DDDs of (1) anxiolytics, sedatives and hypnotics and (2) antidepressants.…”

Impact on In‐ and Out‐of‐Hospital Drug Prescriptions of Including a More Expensive Me‐Too Antidepressant in a Hospital Drug Formulary: a Controlled Longitudinal Study

“…Trends in out-of-hospital desvenlafaxine and venlafaxine (defined daily doses per 1000 inhabitants per day [DDD/TID]) impact would be mitigated by large discounts from the pharmaceutical industry), 7,[9][10][11]35 but can also be transmitted to out-of-hospital costs (though in our case, these did not turn out to be statistically significant in the model with control group).…”

“…Although there are descriptive studies that show high intrahospital adherence to HDF medications (since compliance is not mandatory and there may be medication use outside of the formulary), 12,[36][37][38][39][40] there are very few studies which analyze the effect of alterations in an HDF on the two healthcare settings (in-hospital and out-of-hospital). [9][10][11] On the other hand, there are other kind of studies which show involvement of the hospital in changes in prescribing patterns [41][42][43] and furnish evidence of the specific contextual factors that can affect the impact sought with this type of intervention. This current study allows us to identify the effect of a change not previously analyzed (the inclusion of a new, higher-cost me-too drug) in a therapeutic group not previously studied (SNRIs).…”

“…To control for the possible autocorrelation of residuals (perturbations), we added autoregressive terms to the model. From the β7 regression coefficient, we estimated the annual, long‐term, post‐intervention percentage changes, taking the value prior to the date of the intervention as reference 9,10,22 …”

“…7,8 In addition to the role that hospital drugs formularies (HDFs) can play in hospital prescriptions, they may play an indirect role in primary-care prescriptions through so-called induced prescribing, a field that has remained almost unexplored to date. [9][10][11][12][13] To our knowledge, currently only five studies have been conducted to analyze the impact of a change to the HDF, three of which were carried out by our research group, and it seems that the impact induced by a change in HDFs on out-of-hospital drug prescriptions cannot be generalized for all kinds of changes to HDFs or to all therapeutic groups. Other contextual factors such as the commercialization of new drugs or the expiration of patents could also play an important role.…”