Use of State Sequence Analysis in Pharmacoepidemiology: A Tutorial

Abstract

While state sequence analysis (SSA) has been long used in social sciences, its use in pharmacoepidemiology is still in its infancy. Indeed, this technique is relatively easy to use, and its intrinsic visual nature may help investigators to untangle the latent information within prescription data, facilitating the individuation of specific patterns and possible inappropriate use of medications. In this paper, we provide an educational primer of the most important learning concepts and methods of SSA, including measurement of dissimilarities between sequences, the application of clustering methods to identify sequence patterns, the use of complexity measures for sequence patterns, the graphical visualization of sequences, and the use of SSA in predictive models. As a worked example, we present an application of SSA to opioid prescription patterns in patients with non-cancer pain, using real-world data from Italy. We show how SSA allows the identification of patterns in prescriptions in these data that might not be evident using standard statistical approaches and how these patterns are associated with future discontinuation of opioid therapy.

Understanding Patterns of Adherence to Antifibrotic Treatment in Idiopathic Pulmonary Fibrosis: Insights from an Italian Prospective Cohort Study

“…The State Sequence Analysis [15] (SSA) was used to describe the pattern of use of antifibrotics by an individual through weekly adherence sequences. States were defined by the weekly PDC ≥ 75% (yes or not) observed over 52 weeks from the first prescription; the succession of states over time defined the entire antifibrotic utilization pattern of each subject (individual sequence).…”

Discovering patterns in outpatient neurology appointments using state sequence analysis

“…It is a relatively new methodology to healthcare, but a number of studies in the last few years have used SSA. These studies fall into two primary types; those which examine temporal data such as patterns of drug adherence [ 8 , 9 ] or mortality following illness [ 10 ]; and others which study trajectories of care (for example appointment sequences and hospital stays) which are examined in the following paragraph.…”

Antipsychotic utilization trajectories three years after initiating or reinitiating treatment of schizophrenia: A state sequence analysis approach

“…9,17 State Sequence Analysis (SSA), as an innovative method for the analysis of longitudinal sequential data, is largely used in social sciences to describe and visualize longitudinal patterns such as life course or employment status trajectories. [18][19][20][21][22][23] Recently, this method has been used in health sciences to describe and analyze care trajectories, 24 although, to our knowledge, only a few studies have used this approach to describe drug utilization trajectories, 17,25,26,27 and none to describe trajectories of different AP. From the perspective of SSA, an AP utilization trajectory consists of a sequence of successive categorical states and transitions, each corresponding to a patient's record of AP use at a given time.…”