DATASUS is an administrative claims database and represents healthcare data from SUS, the largest government-run public health insurance system in the world by number of beneficiaries/users. From its inception, DATASUS was intended to enable researchers conduct health resource utilization and epidemiological studies relevant to the Brazilian population.[10, 24] In the case of RA, to date, DATASUS has not been evaluated as a relevant and reliable data source for pharmacoepidemiologic research. Our study focused on DMARD therapies in RA among prevalent and new users, examining switching and discontinuation patterns over the last decade. We also evaluated determinants of initiation and/or switching to a novel therapy in this population.
In this study, we identified a large and representative sample of 250,251 individuals diagnosed with RA in DATASUS, treated with DMARDs between January 1st, 2010, and December 31st, 2020. The study cohort had a median age of 55 years, mostly female (82.8%), and white (57.7%). The characteristics of our cohort corroborated findings from earlier studies in Brazil.[11, 19, 25, 26] Results from the REAL study (2020) of 1,115 patients with RA treated at eleven public (SUS) centers across Brazil reported a median age of 56.6 years, 89.5% female, and 58.6% white.[26] Although potential genetic factors may contribute to RA predisposition among whites/Caucasians (proposed in REAL study),(26) and more than half (52.9%) of patients in our study were from the south and southeast regions in Brazil where there is a high proportion of white/Western European ethnic population, this region benefits from better access to healthcare from a higher concentration of physicians.[27, 28] The geographic heterogeneity found in our study is in line with previous Brazilian perspectives findings of patients with RA.[29]
In Brazil, pharmacoepidemiology research faces challenges, not from a lack of data, but rather from the lack of data integration and linked databases within SUS to ensure complete capture of the disease journey.[30] As with similar approaches outside of Brazil,[6, 14, 15, 17, 19] health record linkage methods were used to bridge data at the patient level across in-patient and out-patient data sets, thereby ensuring the longitudinal data capture across these settings to capture the full patient journey in RA.[18, 30] Although, DATASUS has the advantage in capturing information from SUS comprehensive public health system, between 22–25% of the Brazilian population has supplementary health insurance.[11, 12, 31] This means that private insured patients may seek SUS to access high-cost medications while not seeking additional care within SUS. Because of this limitation in comprehensive data capture, we built a non-SUS exclusive cohort and noted minor differences in treatment patterns in RA compared with the SUS-exclusive population, though no formal comparisons were performed.
The Brazilian Ministry of Health provides free access to nearly all currently approved synthetic and biological DMARDs for the treatment of RA within SUS, and new technologies are continuously assessed for possible incorporation.[32] The first anti-TNF agent to be introduced in SUS for RA was infliximab in 2002, followed by etanercept and adalimumab in 2006.[32] Currently, the Brazilian protocol for the management of RA does incorporate all relevant concepts and resources with proven efficacy in clinical trials.[26] There are concerns regarding extrapolating benefit-risk exclusively from clinical trial evidence to conditions in the real world, thus the critical role of identifying representative data sources that allow researchers to measure actual patterns of RA management in the real world.
In this study, we captured treatment patterns of newer and traditional biologic and targeted synthetic DMARDs that were introduced in Brazil over the last decade for treatment for RA. As expected per clinical guidelines and time on market in Brazil, adalimumab and etanercept were the most prevalent drugs used for RA treatment in the SUS-exclusive and non-SUS-exclusive cohorts over the study period. Similar patterns of etanercept and adalimumab dominance over other newly introduced agents have also been observed in other countries, such as the United States and Taiwan. [25, 33, 34] Similarly, although tocilizumab and abatacept have emerged as newer DMARD treatments of choice in recent years, the follow-up time was limited compared to prevalent drugs. And, to address pharmacoepidemiologic questions centered on safety events of interest, which may be valid and deemed to be captured consistently in SUS, cycling between DMARDs and new drugs must be carefully considered over a longer length of follow-up time available for study. Because of SUS's comprehensive reimbursement for DMARDs, it is possible to analyze pattern shifts in treatment preference over time in parallel with physicians' experiences and clinical outcomes.
Switching among biologic therapies is considered when the first course of treatment demonstrates insufficient efficacy or adverse effects, although patient and physician preference may also play a role.[35] Furthermore, studies show that up to 40% of patients do not respond to available treatments, including DMARDs.[36] Based on previous observations, switching was considered an alternate approach for controlling disease progression and severity.[37] As anticipated based on approved indications,[25] we observed that patients treated with etanercept, adalimumab, and other index b/tsDMARDs in first line, switched to other b/tsDMARDs, mainly tocilizumab and abatacept for the second line RA treatment. Future patient and physician centered research may elicit details on reasons for drug treatment switching, which we could not address in DATASUS, an administrative claims database.
We evaluated patient characteristics found in DATASUS as potential predictors of initiating or switching to a tsDMARD, tofacitinib, a new therapeutic intervention representing a novel mechanism of action (JAKi) introduced in SUS in 2017 (approved for second or third line therapy in RA according to Clinical Guideline of Ministry of Health).[38] Independent predictors of switching to and/or initiating tsDMARD included distance to clinic, number of previous biologic DMARDs, and being exclusively dependent on SUS for health insurance coverage. Individuals with RA who reside more than 160 km from a SUS healthcare center were 43% less likely to initiate tsDMARD and 18% more likely to switch from bDMARD to tsDMARD. Further studies are needed to effectively evaluate the influence of distance to clinic and treatment choice, but we hypothesize that, based on preference studies and appreciation of benefits associated with oral medications, physicians may be less likely to prescribe tsDMARD as first-line treatment for patients who live further away if they do not have an established relationship or have experience managing their disease using bDMARDs.[39] Conversely, the added convenience of an oral alternative may viewed as favorable or practical for patients who have been treated in the past with other bDMARDs.
Strengths related to the study included its large sample size, efficiency, generalizability, high validity, completeness of prescription drug information, and mapping of data for drug utilization research needs. Retrospective analyses of DATASUS make it possible to assess and compare many available biologics at the same time. A big advantage of DATASUS was the broad coverage in providing detailed information on patients with RA, as it encompasses 77.5% of the Brazilian population.[11]
Our study had limitations stemming from the inconsistent and incomplete data collection methods for DATASUS. In particular, limited clinical data, questionable accuracy of disease diagnosis, and the absence of cross-validated and linkage of healthcare data in Brazil are key challenges for studies of chronic diseases like RA.[1, 11] Also, observational research studies may be subject to confounding and misclassification biases due to unmeasured and unknown variables associated with drug exposure. Disease activity is contributing factor that could not be evaluated using DATASUS. Smaller studies like the REAL study have longer follow up and capture disease activity and clinical response, which are not possible to ascertain from DATASUS claims.[26] Also, there may be an absence in consistency of data capture for information such as duration and doses of each medication as well as reasons for discontinuation. Future pharmacoepidemiology studies focused on safety objectives may need to focus on SUS-exclusive populations within DATASUS where health-related encounters, treatments, and procedures are consistently captured, granted that the outcomes of interest are measured and validated. Although multivariate regression analysis has been applied to control potential confounders, the independent effects of the treatment group on the decision of intra- or inter-biologic switching may be subject to omitted-variable biases, because some important information, such as laboratory data, disease duration, and disease activity, was not available in the dataset. Data fragmentation and accessibility problems in Brazil can be resolved systematic databases, further classified into SUS-exclusive and non-SUS-exclusive groups to optimize the ability to conduct pharmacoepidemiology research.
As with other health insurance administrative claims databases, DATASUS has the potential to be a valuable source of real-world data when handled with pharmacoepidemiologic principles of scientific study design and analyses. Often regarded as the foundation for pharmacoepidemiologic research, claims data are used for post-marketing drug surveillance, cost-effectiveness evaluations, and when evaluating preventive therapeutic strategies.[7, 17, 40] Our analyses of DATASUS provided insights on the treatment patterns relevant to individuals living with RA in Brazil that may contribute to a more accurate prediction of future healthcare planning, helping to adapt the Brazilian healthcare system to these changes.