Exploring New Zealand prescription data using sequence symmetry analyses for predicting adverse drug reactions

The State of Use and Utility of Negative Controls in Pharmacoepidemiologic Studies

Uses of real-world data in drug safety and effectiveness studies are often challenged by various sources of bias. We undertook a systematic search of the published literature through September 2020 to evaluate the state of use and utility of negative controls to address bias in pharmacoepidemiologic studies. Two reviewers independently evaluated study eligibility and abstracted data. Our search identified 184 eligible studies for inclusion. Cohort studies (115, 63%) and administrative data (114, 62%) were, respectively, the most common study design and data type used. Most studies used negative control outcomes (91, 50%), and for most studies the target source of bias was unmeasured confounding (93, 51%). We identified 4 utility domains of negative controls: 1) bias detection (149, 81%), 2) bias correction (16, 9%), 3) P-value calibration (8, 4%), and 4) performance assessment of different methods used in drug safety studies (31, 17%). The most popular methodologies used were the 95% confidence interval and P-value calibration. In addition, we identified 2 reference sets with structured steps to check the causality assumption of the negative control. While negative controls are powerful tools in bias detection, we found many studies lacked checking the underlying assumptions. This article is part of a Special Collection on Pharmacoepidemiology.

Prescribing cascades in ambulatory care: A structured synthesis of evidence

The strength of evidence for specific ambulatory care prescribing cascades, in which a marker drug is used to treat an adverse event caused by an index drug, has not been well characterized. To perform a structured, systematic, and transparent review of the evidence supporting ambulatory care prescribing cascades. Ninety-four potential prescribing cascades identified through a previously published systematic review. Systematic search of the literature to further characterize prescribing cascades. (1) Grading of evidence based on observational studies investigating associations between index and marker drugs, including: Level I-strong evidence [i.e. multiple high-quality studies]; Level II-moderate evidence [i.e. single high-quality study]; Level III-fair evidence [no high-quality studies but one or more moderate-quality studies]; and Level IV-poor evidence [other]. (2) Listing of the adverse event associated with the index drug in the product's United States Food and Drug Administration (FDA) label. (3) Synthesis of the evidence supporting mechanisms linking index drugs and associated adverse events. Of 99 potential cascades, 94 were supported by one or more confirmatory observational studies and were therefore included in this review. The 94 cascades related to 30 types of adverse drug reactions affecting 10 different anatomic/physiologic systems and were investigated by a total of 88 confirmatory studies, including prescription sequential symmetry analysis (n = 51), cohort (n = 30), and case-control (n = 7) studies. Overall, the evidence from observational studies was strong for 18 (19.1%) prescribing cascades, moderate for 61 (64.9%), fair for 13 (13.8%), and poor for 2 (2.1%). Although the evidence supporting mechanisms that link index drugs and associated adverse events was variable, FDA labels included information about the adverse event associated with the index drug for most (n = 86) but not all of the 94 prescribing cascades. Although we identified 18 of 94 prescribing cascades supported by strong clinical evidence and most adverse events associated with index drugs are included in FDA label, the evidentiary basis for prescribing cascades varies, with many requiring further evidence of clinical relevance.

Modifiable statin characteristics associated with potential statin-related prescribing cascades

STUDY OBJECTIVE

Clinicians may prescribe new medications (marker drug) to treat statin-related (index drug) adverse events, constituting a prescribing cascade. We aimed to identify modifiable statin characteristics (intensity and individual statin agents) associated with lower risk of prescribing cascades to inform clinical decisions in the presence of statin-related adverse events.

DESIGN

A secondary analysis based on our previous work, a high-throughput sequence symmetry analysis screening for potential statin-related prescribing cascades.

DATA SOURCE

MarketScan Commercial and Medicare Supplemental Insurance claims databases between 2005 and 2019.

PATIENTS

Adults who initiated a statin between 2007 and 2018, and who were continuously enrolled in the same healthcare plan for at least 720 days before and 360 days after statin initiation.

INTERVENTION

Among the previously identified 57 potential prescribing cascades, 42 statin-marker class dyad with a sample size of ≥ 500 were assessed in this study.

MEASUREMENTS

We measured patients' baseline characteristics within -360 days of statin initiation and reported by modifiable statin characteristics. We also performed logistic regression and reported the adjusted odds ratios (aOR) with 95% confidence intervals (CI) of modifiable statin characteristics after adjusting for baseline characteristics.

MAIN RESULTS

We identified 1,307,867 statin initiators who met the study criteria (21% elderly, 52% female). Compared with patients initiating low-intensity statins, those initiating moderate- or high-intensity statins had significantly greater odds to develop 29 (69%) prescribing cascades, including antidiabetic drugs such as dipeptidyl peptidase 4 (DPP-4) inhibitors (aOR 1.22; 95% CI, 1.11-1.35) and glucagon-like peptide-1 (GLP-1) analogs (aOR 1.31; 95% CI, 1.16-1.47), and opioids (aOR 1.18; 95% CI, 1.13-1.23). Individual statin agent selection also had a differential effect on 34 (81%) of the prescribing cascades. For example, compared with simvastatin initiators, the probability of initiating osmotically acting laxatives was significantly higher for lovastatin initiators (aOR 1.09; 95% CI, 1.03-1.15) and significantly lower in atorvastatin initiators (aOR 0.92; 95% CI, 0.89-0.94).

CONCLUSION

Compared with low-intensity statins, high-intensity statins are associated with increased risk in many potential prescribing cascades, while the choice of individual statin agents affects the risk of prescribing cascades bidirectionally.

Prescribing Cascades with Recommendations to Prevent or Reverse Them: A Systematic Review

BACKGROUND

To reduce prescribing cascades occurring in clinical practice, healthcare providers require information on the prescribing cascades they can recognize and prevent.

OBJECTIVE

This systematic review aims to provide an overview of prescribing cascades, including dose-dependency information and recommendations that healthcare providers can use to prevent or reverse them.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was followed. Relevant literature was identified through searches in OVID MEDLINE, OVID Embase, OVID CINAHL, and Cochrane. Additionally, Web of Science and Scopus were consulted to analyze reference lists and citations. Publications in English were included if they analyzed the occurrence of prescribing cascades. Prescribing cascades were included if at least one study demonstrated a significant association and were excluded when the adverse drug reaction could not be confirmed in the Summary of Product Characteristics. Two reviewers independently extracted and grouped similar prescribing cascades. Descriptive summaries were provided regarding dose-dependency analyses and recommendations to prevent or reverse these prescribing cascades.

RESULTS

A total of 95 publications were included, resulting in 115 prescribing cascades with confirmed adverse drug reactions for which at least one significant association was found. For 52 of these prescribing cascades, information regarding dose dependency or recommendations to prevent or reverse prescribing cascades was found. Dose dependency was analyzed and confirmed for 12 prescribing cascades. For example, antipsychotics that may cause extrapyramidal syndrome followed by anti-parkinson drugs. Recommendations focused on dosage lowering, discontinuing medication, and medication switching. Explicit recommendations regarding alternative options were given for three prescribing cascades. One example was switching to ondansetron or granisetron when extrapyramidal syndrome is experienced using metoclopramide.

CONCLUSIONS

In total, 115 prescribing cascades were identified and an overview of 52 of them was generated for which recommendations to prevent or reverse them were provided. Nonetheless, information regarding alternative options for managing prescribing cascades was scarce.

High-throughput screening for prescribing cascades among real world statin initiators

PURPOSE

Statins are among the most prevalent medications prescribed and associated with adverse events that may prompt additional treatment (i.e., a prescribing cascade). No comprehensive assessment of statin-related prescribing cascades has been performed to our knowledge.

METHODS

We utilized sequence symmetry analysis to iteratively screen prescribing sequences of all therapeutic classes ("marker" classes) based on Level 4 Anatomical Therapeutic Chemical codes among adult statin initiators, using IBM Marketscan commercial and Medicare supplemental claims databases (2005-2019). Order of initiation and secular trend-adjusted sequence ratios were calculated for each statin-marker class dyad, among marker class initiators ±90 days of statin initiation. Among signals classified as prescribing cascades, we calculated naturalistic number needed to harm (NNTH) within 1 year as the inverse of the excess risk among exposed.

RESULTS

We identified 2 265 519 statin initiators (mean ± SD age, 56.4 ± 12.0 years; 48.7% women; 7.5% with cardiovascular disease). Simvastatin (34.4% of statin initiators) and atorvastatin (33.9%) were the most commonly initiated statins. We identified 160 significant statin-marker class dyad signals, of which 35.6% (n = 57) were classified as potential prescribing cascades. Of the top 25 strongest signals (lowest NNTH), 12 were classified as potential prescribing cascades, including osmotically acting laxatives (NNTH, 44, 95% CI 43-46), opioids + non-opioid combination analgesics (81, 95% CI 74-91), and first-generation cephalosporins (204, 95% CI 175-246).

CONCLUSIONS

Using high-throughput sequence symmetry analysis screening, we identified previously known prescribing cascades as well as potentially new prescribing cascades based on known and unknown statin-related adverse events.

Continued potassium supplementation use following loop diuretic discontinuation in older adults: An evaluation of a prescribing cascade relic

BACKGROUND

The use of a new medication (e.g., potassium supplementation) for managing a drug-induced adverse event (e.g., loop diuretic-induced hypokalemia) constitutes a prescribing cascade. However, loop diuretics are often stopped while potassium may be unnecessarily continued (i.e., relic). We aimed to quantify the occurrence of relics using older adults previously experiencing a loop diuretic-potassium prescribing cascade as an example.

METHODS

We conducted a prescription sequence symmetry analysis using the population-based Medicare Fee-For-Service data (2011-2018) and partitioned the 150 days following potassium initiation by day to assess the daily treatment scenarios (i.e., loop diuretics alone, potassium alone, combination of loop diuretics and potassium, or neither). We calculated the proportion of patients developing the relic, proportion of person-days under potassium alone, the daily probability of the relic, and the proportion of patients filling potassium after loop diuretic discontinuation. We also identified the risk factors of the relic.

RESULTS

We identified 284,369 loop diuretic initiators who were 8 times more likely to receive potassium supplementation simultaneously or after (i.e., the prescribing cascade), rather than before, loop diuretic initiation (aSR 8.0, 95% CI 7.9-8.2). Among the 66,451 loop diuretic initiators who subsequently (≤30 days) initiated potassium, 20,445 (30.8%) patients remained on potassium after loop diuretic discontinuation, and 9365 (14.1%) patients subsequently filled another potassium supplementation. Following loop diuretic initiation, 4.0% of person-days were for potassium alone, and daily probability of the relic was the highest after day 90 of loop diuretic initiation (5.6%). Older age, female sex, higher diuretic daily dose, and greater baseline comorbidities were risk factors for the relic, while patients having the same prescriber or pharmacy involved in the use of both medications were less likely to experience the relic.

CONCLUSIONS

Our findings suggest the need for clinicians to be aware of the potential of relic to avoid unnecessary drug use.

Prescribing cascades in community-dwelling adults: A systematic review

The misattribution of an adverse drug reaction (ADR) as a symptom or illness can lead to the prescribing of additional medication, referred to as a prescribing cascade. The aim of this systematic review is to identify published prescribing cascades in community-dwelling adults. A systematic review was reported in line with the PRISMA guidelines and pre-registered with PROSPERO. Electronic databases (Medline [Ovid], EMBASE, PsycINFO, CINAHL, Cochrane Library) and grey literature sources were searched. Inclusion criteria: community-dwelling adults; risk-prescription medication; outcomes-initiation of new medicine to "treat" or reduce ADR risk; study type-cohort, cross-sectional, case-control, and case-series studies. Title/abstract screening, full-text screening, data extraction, and methodological quality assessment were conducted independently in duplicate. A narrative synthesis was conducted. A total of 101 studies (reported in 103 publications) were included. Study sample sizes ranged from 126 to 11 593 989 participants and 15 studies examined older adults specifically (≥60 years). Seventy-eight of 101 studies reported a potential prescribing cascade including calcium channel blockers to loop diuretic (n = 5), amiodarone to levothyroxine (n = 5), inhaled corticosteroid to topical antifungal (n = 4), antipsychotic to anti-Parkinson drug (n = 4), and acetylcholinesterase inhibitor to urinary incontinence drugs (n = 4). Identified prescribing cascades occurred within three months to one year following initial medication. Methodological quality varied across included studies. Prescribing cascades occur for a broad range of medications. ADRs should be included in the differential diagnosis for patients presenting with new symptoms, particularly older adults and those who started a new medication in the preceding 12 months.

Evaluating the use of prescription sequence symmetry analysis as a pharmacovigilance tool: A scoping review

BACKGROUND

The (prescription) sequence symmetry analysis (PSSA) design has been used to identify potential prescribing cascade signals by assessing the prescribing sequence of an index drug relative to a marker drug presumed to treat an adverse drug event provoked by the index drug.

OBJECTIVES

This review aimed to explore the use of the PSSA design as a pharmacovigilance tool with a particular focus on the breadth of identified signals and advances in PSSA methodology.

METHODS

We searched Embase, PubMed/Medline, Google Scholar, Web of Science and grey literature to identify studies that used the PSSA methodology. Two reviewers independently extracted relevant data for each included article. Study characteristics including signals identified, exposure time window, stratified analyses, and use of controls were extracted.

RESULTS

We identified 53 studies which reported original results obtained using PSSA methodology or quantified the validity of components of the PSSA design. Of those, nine studies provided validation metrics showing reasonable sensitivity and high specificity of PSSA to identify prescribing cascade signals. We identified 340 unique index drug - marker drug signals published in the PSSA literature, representing 281 unique index - marker pharmacological class dyads (i.e., unique fourth-level Anatomical Therapeutic Chemical [ATC] classification dyads). Commonly observed signals were identified for index drugs acting upon the nervous system (34%), cardiovascular system (21%), and blood and blood-forming organs (15%), and many marker drugs were related to the nervous system (25%), alimentary tract and metabolism (23%), cardiovascular system (17%), and genitourinary system and sex hormones (14%). Negative controls and positive controls were utilized in 21% and 13% of studies, respectively.

CONCLUSIONS

The PSSA methodology has been used in 53 studies worldwide to detect and evaluate over 300 unique prescribing cascades signals. Researchers should consider sensitivity analyses incorporating negative and/or positive controls and additional time windows to evaluate time-varying biases when designing PSSA studies.

Assessment of Medication Safety Using Only Dispensing Data

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the published studies that have been used to generate evidence on the safety of medicine use when only medication dispensing data are available.

RECENT FINDINGS

Medication dispensing databases are increasingly available for research on large populations, particularly in countries that provide universal coverage for medicines. These data are often used for drug utilisation studies to identify inappropriate medicine use at the population level that may be associated with known safety issues. Lack of coded diagnoses, to identify outcomes, and lack of data on confounders can limit use of these data in practice for medication safety assessment. To overcome these issues, studies have exploited the fact that symptoms of adverse effects of medications can be treated with other medications, for example antidepressants to treat depression or oxybutynin to treat urinary incontinence. The challenge of unmeasured confounding has been addressed by implementing self-controlled study designs that use within-person comparisons and provide inherent control for confounding. Prescription sequence symmetry analysis (SSA) is a within-person study design that has been demonstrated as a useful tool for safety signal generation in dispensing data.

SUMMARY

Using medicine initiation as a proxy for the development of adverse events can help to generate evidence of the safety of medicines when only medication dispensing data are available. Careful consideration, however, should be given to the sensitivity and specificity of the proxy medicine for the adverse event and potential for time-varying confounding due to trends in medicine utilisation. Data-mining approaches using dispensing data have the potential to improve safety assessments; however, the challenge of unmeasured confounding with these methods remains to be investigated.