Participants with age 18 and over who received a first prescription of single-ingredient paracetamol or ibuprofen in 2012 will be enrolled. Their status with respect to prior gastrointestinal bleeding, myocardial infarction, stroke, or kidney disease will be assessed based on the presence or absence of a diagnosis in the 2 years prior to the index date. This observational study will evaluate whether new users of paracetamol have a higher prevalence of certain conditions (gastrointestinal bleeding, myocardial infarction, stroke or kidney disease) in their history when compared to new users of ibuprofen, propensity scores and outcome models.

Participants with age 18 and over who received a first prescription of single-ingredient ibuprofen in 2012 will be enrolled. Their status with respect to prior gastrointestinal bleeding, myocardial infarction, stroke, or kidney disease will be assessed based on the presence or absence of a diagnosis in the 2 years prior to the index date. This observational study will evaluate whether new users of paracetamol have a higher prevalence of certain conditions (gastrointestinal bleeding, myocardial infarction, stroke or kidney disease) in their history when compared to new users of ibuprofen, propensity scores and outcome models.

Participants receiving first prescriptions of single-ingredient paracetamol or ibuprofen will be assessed to analyze whether participants with paracetamol were more likely to have had an ibuprofen-related contraindication than participants with ibuprofen.

The potential to control for channeling bias will be examined. It will also assess whether there will be sufficient overlap in propensity scores to allow for adequate adjustment to control for bias due to channeling. The propensity score is the estimated probability of receiving a treatment (paracetamol), based on the available data, ranges from 0 to 1. The higher the score, the more likely to be treated with paracetamol.