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

  • Paediatric Population (< 18 years)
    • Neonate
      • Term newborn infants (0 – 27 days)
    • Infants and toddlers (28 days – 23 months)
    • Children (2 to < 12 years)
    • Adolescents (12 to < 18 years)
  • Adult and elderly population (≥18 years)
    • Adults (18 to < 65 years)
      • Adults (18 to < 46 years)
      • Adults (46 to < 65 years)
    • Elderly (≥ 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.