Risk of upper gastrointestinal bleed according to initial care contact for spinal pain: protocol for a matched retrospective cohort study

Background: Upper gastrointestinal bleeds (UGIBs) are serious adverse events potentially induced by non-steroidal anti-inflammatory drugs (NSAIDs), which are commonly used for spinal pain. Spinal manipulative therapy (SMT) is efficacious for spinal pain and associated with a lower likelihood of opioid prescription and related adverse events in these patients, yet its impact on NSAID-related adverse events and prescriptions remain unexplored. We hypothesize that among adults with a new episode of spinal pain, those receiving SMT will have a significantly lower risk of UGIB compared to matched controls evaluated in an outpatient setting, secondarily exploring non-aspirin NSAID prescription. Methods: We will query a large US health records-based data resource (TriNetX, LLC) for adults (age ≥ 18 years) with a new episode of spinal pain from one to 15 years prior to the query date without prior UGIB or recent non-aspirin NSAID prescription. Cohorts will be divided into (1) chiropractor-administered SMT and (2) outpatient care without SMT (i.e., usual medical care); using propensity score matching to account for risk factors for UGIB. We will examine the risk ratio (RR; primary outcome) and risk difference of UGIBs in patients undergoing SMT compared to usual medical care over a one year follow-up window, and pursue a sensitivity analysis including unspecified GI bleeds, examine risk of NSAID prescription, and negative control outcomes.