Impact of EU label changes for hydroxyzine products: post-referral prescribing trends

Study type

• Study topic:
  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Drug utilisation

  Effectiveness study (incl. comparative)
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Cohort

  Other
• Non-interventional study design, other:
  Population-based longitudinal study, Time series analysis

Study drug and medical condition

• Study drug International non-proprietary name (INN) or common name:
  HYDROXYZINE

Population studied

• Short description of the study population:
  The study population consisted of all patients registered within each data source at any time during the study period. The start of follow-up for a patient was defined as date of registration with the general practice (CPRD and PHARMO), or date of first recorded prescription or any secondary care diagnosis (Denmark and; Scotland). A patient’s index date was the latest of the study period start date (dependent on each data source), the date of birth, or their first database follow up date plus 1 year (to allow sufficient time for data on baseline covariates to be collected). A patient’s end of follow-up was the date of the first occurrence of the following: death (all databases); end of study period (varies between countries); end of registration (end of registration would not significantly affect data from Denmark and Scotland because they use national data that captures patients moving within the health system). A patient was included for analysis in a time period if the first and last day both lay between the patient’s index date and their last follow up date, so the analyses only included patients who are observable for the entire timeperiod.
• Age groups:
  Term newborn infants (0 – 27 days)

  Infants and toddlers (28 days – 23 months)

  Children (2 to < 12 years)

  Adolescents (12 to < 18 years)

  Adults (18 to < 46 years)

  Adults (46 to < 65 years)

  Adults (65 to < 75 years)

  Adults (75 to < 85 years)

  Adults (85 years and over)
• Estimated number of subjects:
  100000

Study design details

• Main study objective:
  The three main objectives are as follows: To determine prescription patterns of hydroxyzine containing products. To determine prescribers compliance with recommendations. To determine prescription patterns of alternative medicines prescribed in patients where hydroxyzine has previously been prescribed.
• Data analysis plan:
  The proposed primary analysis will address the three objectives given above using interrupted time series regression to fit time trends to each series of time period data for each country. Using regression modelling we will evaluate: (1) The baseline slope before the intervention time point, (2) The change in slope from the baseline trend to the post-intervention trend, (3) The immediate change associated with the intervention time point. The effect of the intervention for each country will be represented either by a step function, or by a continuous linear function representing gradual implementation (interrupted time series analysis). This choice, and whether it is necessary to model any trends prior to the intervention time point, will be decided on visual inspection of the data. The analysis will be done by data source initially, and only pooled if the statistical models do not differ significantly between data sources.

Documents

Study results

EMA_hydroxyzine_final revised_061219

Study, other information

Hydroxyzine abstract_Final_040320

Study publications

Morales DR, Macfarlane T, MacDonald TM, Hallas J, Ernst MT, Herings RM, Smits E…