Abstract
Background and Purpose
Endovascular coiling therapy is increasingly popular for obliteration of unruptured intracranial aneurysms but older patients face higher procedural risks and shorter periods during which an untreated aneurysm may rupture causing subarachnoid hemorrhage. We assessed trends in clipping and coiling of unruptured intracranial aneurysms, outcomes after clipping and coiling of unruptured intracranial aneurysms, and in subarachnoid hemorrhage among Medicare beneficiaries.
Methods
Using 2000–2010 MEDPAR data, we identified 2 cohorts of patients admitted electively for clipping or coiling of an unruptured aneurysm: 1) utilization cohort (2000–2010): patients ≥65 years enrolled ≥1 month in a given year; 2) outcomes cohort (2001–2010): patients ≥ 66 years of age enrolled in Medicare for ≥1 year. We calculated rates of clipping, coiling, and subarachnoid hemorrhage per 100,000 Medicare beneficiaries. We tested for trends in the risk of in-hospital mortality and complications, discharge destination, 30-day mortality, 30-day readmissions, and length of hospitalization.
Results
Characteristics of patients undergoing clipping (N=4,357) or coiling (N=7,942) did not change appreciably. Overall, 30-day mortality, in-hospital complications, and readmissions decreased, generally reaching their lowest levels in 2008–2010 (1.6%, 25.0%, and 14.5% for clipping and 1.5%, 13.8%, and 11.0% for coiling, respectively). Procedural treatment rates per 100,000 beneficiaries increased from 1.4 in 2000 to 6.0 in 2010, driven mainly by increased use of coiling but subarachnoid hemorrhage rates did not decrease.
Conclusions
While outcomes tended to be more favorable over time, increased preventative treatment of unruptured intracranial aneurysms among Medicare beneficiaries did not result in a population-level decrease in subarachnoid hemorrhage rates.
Keywords: Neurosurgery, Neurosurgery, Coil embolization, Aneurysm, Medicare, Mortality
INTRODUCTION
Approximately 3% of the general population harbors an unruptured intracranial aneurysm (UIA).1 UIA is not a benign condition because aneurysm rupture can lead to subarachnoid hemorrhage (SAH). Mortality risks are between 30% and 45% for aneurysmal SAH and up to 20% of survivors will be permanently disabled.2 Thus, interventional procedures are often used to obliterate an UIA with the goal of eliminating rupture risk and SAH. However, the annual risk of rupture for most UIAs tends to be low (between 0.5% and 1%)3–5 and between 50% and 80% of aneurysms do not rupture over a person’s lifetime.6 Decisions about UIA management must therefore balance the risks of procedures used to obliterate the UIA versus the natural history risk.
Patient age is a key decision-making factor, since older patients face higher procedural risks4,7 and a shorter period of natural history risk. Accordingly, the overall benefit of interventions for UIAs is likely to vary by age. However, 20–25% of patients with UIAs who undergo clipping or coiling are 65 years old or older,7,8 and little is known about population-level trends in the use and outcomes of these procedures in this patient group. The objective of this study was to evaluate trends in the use of clipping and coiling for UIAs, changes in 30-day outcomes after clipping and coiling of UIAs, and changes in the occurrence of SAH among Medicare beneficiaries over time.
METHODS
Data Sources
We conducted a retrospective cohort study using the Medicare Provider Analysis and Review (MEDPAR) Research Identifiable Files (2000–2010), the Beneficiary Annual Summary File (2000–2010), and the American Hospital Association’s (AHA) Annual Survey Database 2009. MEDPAR contains claims for services provided to Medicare fee-for-service beneficiaries in inpatient and skilled nursing facility settings. Patient demographic characteristics, discharge diagnoses, procedures, admission type, and discharge disposition are provided at the encounter-level and patients can be tracked longitudinally. The Beneficiary Annual Summary File contains enrollment information and death information, up to three years after discharge.9
Study Population
The study population consisted of two cohorts, one to describe trends in utilization of clipping and coiling (utilization cohort; 2000–2010) and one to describe changes in patient characteristics and outcomes over time (outcomes cohort; 2001–2010). The utilization cohort consisted of beneficiaries at least 65 years of age enrolled at least 1 month in a given year as the denominator. Patients could contribute to the numerator by being admitted to the hospital electively for an UIA (ICD-9 CM code: 437.3) that was clipped (ICD-9-CM codes: 39.51) or coiled (ICD-9-CM codes: 39.52, 39.72, 39.75, 39.76, 39.79) only once in a given year but could contribute again in later years if they underwent another procedure. The outcomes cohort consisted of patients aged 66 years of age and older that were continuously enrolled in Medicare for at least year (baseline period) prior to being admitted electively for the clipping or coiling of a UIA. Patients undergoing more than one procedure were categorized according to their first procedure. If clipping and coiling occurred on the same day, patients were assumed to have undergone a conversion from coiling to clipping and were categorized as having undergone coiling.
Outcomes
The outcomes of interest included mortality (in-hospital, 30-day), 30-day hospital readmissions, length of stay, and discharge disposition (dead, home without home healthcare, transferred to acute care, transferred to long-term care). A composite in-hospital endpoint consisting of potential complications of procedural treatment included stroke, hydrocephalus, ventriculostomy, ventricular shunt, tracheotomy, prolonged mechanical ventilation, and postoperative neurological, cardiovascular, or surgical site complications (supplemental Table I). We followed patients from the procedure date until the earliest of the following events: the outcomes, death, loss of Medicare eligibility, or the end of the study period (December 31st, 2010).
Study Variables
We obtained patient date of birth, sex, and race (which we categorized as white or not-white). Using algorithms validated in the Medicare population whenever possible, we identified past-year hospitalizations of ischemic stroke, hemorrhagic stroke, myocardial infarction, coronary artery bypass graft, atrial fibrillation, congestive heart failure, ischemic heart disease, diabetes, hypertension, hyperlipidemia, chronic kidney disease, chronic obstructive pulmonary disorder (COPD), and cancer (supplemental Table II). To assess overall comorbidity burden, we calculated the Elixhauser comorbidity score.10 Performing hospitals were described in terms of ownership (government, investor-owned, not-for-profit), metropolitan location (yes/no), and teaching affiliation (yes/no). To calculate hospital procedural volume, we counted the number of procedures performed among Medicare beneficiaries in the year preceding the index date in a given center.
Analysis
Using the utilization cohort, we calculated the yearly rate of UIA clipping and coiling procedures per 100,000 Medicare beneficiaries overall and stratified by age group (65–74 vs. ≥75 years). We assessed changes in patient characteristics and in performing centers over time by aggregating patients in the outcomes cohort into three time blocks (2001–2003, 2004–2007, 2008–2010) and report percentages for categorical variables and means and standard deviations and/or medians and interquartile ranges for continuous variables. These time blocks were selected based on the fact that patient characteristics did not change appreciably from year to year and on the assumption that any changes in outcomes would likely be driven by changes in rates of uptake or procedural technology. Due to the baseline period requirement (continuous eligibility for at least one year) for the outcomes cohort, patient characteristics and outcomes are reported for clipping and coiling of UIAs from 2001 onward. We report unadjusted risks and 95% confidence intervals (CIs) for outcomes, derived from Kaplan-Meier estimators by procedure across time blocks. We tested for trends over the time blocks using Jonckheere-Terpstra tests for in-hospital outcomes, Spearman rank order correlation test for medians, t-test from linear regression for means, and type III Wald Chi-Squared test for peri-procedural outcomes.
Using a validated algorithm,11 we estimated rates of SAH per 100,000 beneficiaries over the study period, age- and sex-standardized to the 2010 Medicare population. We used SAS 9.4 (The SAS Institute, Cary, NC) for all analyses. The institutional review board of Weill Cornell Medical College approved the study.
RESULTS
Trends in UIA Clipping and Coiling
Between 2001 and 2010, 4,357 patients with UIAs underwent clipping and 7,942 patients underwent coiling. Rates of UIA clipping or coiling increased steadily between 2000 and 2010 from 1.4 to 6.0 procedures per 100,000 Medicare beneficiaries (Figure 1). The sharpest increases in preventative UIA treatment occurred between 2001 and 2004 and from 2008 to 2010, driven mainly by increases in coiling. Rates of clipping were stable over time at 1.5 per 100,000 Medicare beneficiaries whereas coiling increased from 0.3 in 2000 to 4.3 in 2010 per 100,000 Medicare beneficiaries. The composition of the population undergoing the procedures between 2000 and 2010 did not change appreciably in terms of age, sex, and census region.
Figure 1.
Rates of Clipping and Coiling of Unruptured Intracranial Aneurysms per 100,000 Medicare Beneficiaries, 2000–2010
Rates of UIA clipping and coiling tended to increase more among Medicare patients aged 65 to 74 than among patients aged ≥75 years (Figure 2). Rates of clipping per 100,000 Medicare beneficiaries increased from 1.88 to 2.84 between 2000 and 2010 for patients aged 65–74 and remained relatively unchanged for patients aged ≥75 years (0.39 in 2000 vs. 0.50 in 2010). The increase in coiling rates per 100,000 beneficiaries from 2000 to 2010 was more pronounced among patients 65–74 (0.39 vs. 5.99) than among those ≥75 years (0.20 vs. 2.38). Overall, the proportion of patients with UIAs undergoing coiling increased from 42.2% to 66.0% in the 66–74 age group and increased from 59.3% to 82.7% in the group aged ≥75 years (supplemental Table III). Characteristics of patients undergoing clipping or coiling did not differ substantially across age groups.
Figure 2.
Rates of Clipping (A) and Coiling (B) of Unruptured Intracranial Aneurysms per 100,000 Medicare Beneficiaries, Stratified by Age, 2000–2010
Changes in Characteristics of Patients with UIAs Undergoing Clipping and Treating Hospitals
Patient demographics did not vary substantially from 2001 to 2010; mean age range was from 70.6 to 71.0 years, between 75.1% and 77.1% were women, and the proportion of white patients ranged from 88.5% to 92.0% (Table 1). There was little change in comorbidity prevalence or in the mean Elixhauser comorbidity score. Characteristics of centers performing UIA clipping changed over the study period; the proportion of not-for-profit institutions increased from 72.2% in 2001–2003 to 77.8% in 2008–2010, the proportion of metropolitan centers increased from 74.5% to 80.0% and the mean Medicare past-year hospital clipping volume increased from 10.8 to 14.9 procedures.
Table 1.
Characteristics of Patients with Unruptured Intracranial Aneurysms Undergoing Clipping or Coiling, 2001–2010
| Clipping | Coiling | |||||
|---|---|---|---|---|---|---|
| 2001– 2003 n=1134 | 2004– 2007 n=1539 | 2008–2010 n=1684 | 2001– 2003 n=977 | 2004– 2007 n=2962 | 2008–2010 n=4003 | |
| Age Mean (SD) | 71.0 (4.0) | 70.7 (3.9) | 70.6 (3.4) | 72.4 (5.0) | 72.5 (5.0) | 72.5 (5.1) |
| Age Group | ||||||
| 66–74 | 930 (82.0%) | 1271 (82.6%) | 1424 (84.6%) | 680 (69.6%) | 2071 (69.9%) | 2760 (68.9%) |
| ≥75 | 204 (18.0%) | 268 (17.4%) | 260 (15.4%) | 297 (30.4%) | 891 (30.1%) | 1243 (31.1%) |
| Female sex | 871 (76.8%) | 1156 (75.1%) | 1299 (77.1%) | 788 (80.7%) | 2311 (78.0%) | 3161 (79.0%) |
| White race | 1043 (92.0%) | 1372 (89.3%) | 1490 (88.5%) | 887 (90.8%) | 2687 (90.7%) | 3524 (88.1%) |
| Region | ||||||
| Midwest | 250 (22.1%) | 306 (19.9%) | 341 (20.2%) | 229 (23.6%) | 675 (22.9%) | 882 (22.1%) |
| Northeast | 176 (15.5%) | 227 (14.8%) | 284 (16.9%) | 140 (14.4%) | 464 (15.7%) | 654 (16.4%) |
| South | 517 (45.7%) | 675 (43.9%) | 649 (38.5%) | 424 (43.7%) | 1315 (44.6%) | 1693 (42.3%) |
| West | 189 (16.7%) | 329 (21.4%) | 410 (24.3%) | 177 (18.2%) | 496 (16.8%) | 769 (19.2%) |
| Comorbidities | ||||||
| Atrial Fibrillation* | 36 (3.2%) | 54 (3.5%) | 49 (2.9%) | 35 (3.6%) | 132 (4.5%) | 182 (4.5%) |
| Cancer | 17 (1.5%) | 53 (3.4%) | 46 (2.7%) | 33 (3.4%) | 85 (2.9%) | 136 (3.4%) |
| Chronic Kidney Disease | 49 (4.3%) | 71 (4.6%) | 112 (6.7%) | 33 (3.4%) | 180 (6.1%) | 345 (8.6%) |
| Chronic Obstructive Pulmonary Disease | 281 (24.8%) | 429 (27.9%) | 368 (21.9%) | 224 (22.9%) | 716 (24.2%) | 897 (22.4%) |
| Coronary Artery Bypass Graft Surgery* | 41 (3.6%) | 43 (2.8%) | 36 (2.1%) | 37 (3.8%) | 67 (2.3%) | 88 (2.2%) |
| Diabetes | 128 (11.3%) | 252 (16.4%) | 260 (15.4%) | 108 (11.1%) | 433 (14.6%) | 725 (18.1%) |
| Heart Failure | 35 (3.1%) | 49 (3.2%) | 23 (1.4%) | 32 (3.3%) | 85 (2.9%) | 79 (2.0%) |
| Hemorrhagic Stroke* | 42 (3.7%) | 40 (2.6%) | 35 (2.1%) | 49 (5.0%) | 94 (3.2%) | 74 (1.8%) |
| Hyperlipidemia | 303 (26.7%) | 548 (35.6%) | 676 (40.1%) | 262 (26.8%) | 1132 (38.2%) | 1801 (45.0%) |
| Hypertension | 782 (69.0%) | 1140 (74.1%) | 1239 (73.6%) | 657 (67.2%) | 2148 (72.5%) | 3032 (75.7%) |
| Ischemic Heart Disease | 84 (7.4%) | 90 (5.8%) | 98 (5.8%) | 65 (6.7%) | 177 (6.0%) | 250 (6.2%) |
| Ischemic Stroke* | 44 (3.9%) | 72 (4.7%) | 89 (5.3%) | 38 (3.9%) | 126 (4.3%) | 204 (5.1%) |
| Myocardial Infarction* | < 10 | 12 (0.8%) | 17 (1.0%) | 13 (1.3%) | 33 (1.1%) | 31 (0.8%) |
| Mean Elixhauser Comorbidity Score (SD) | 3.5 (5.2) | 3.7 (5.3) | 3.4 (5.4) | 2.5 (4.5) | 2.4 (4.6) | 2.4 (4.7) |
| Teaching Hospital | 684 (61.0%) | 1015 (66.3%) | 1147 (68.5%) | 682 (70.2%) | 2028 (69.1%) | 2558 (64.2%) |
| Hospital Ownership | ||||||
| Government | 230 (20.5%) | 295 (19.3%) | 293 (17.5%) | 161 (16.6%) | 559 (19.1%) | 723 (18.1%) |
| Investor- owned | 82 (7.3%) | 85 (5.6%) | 79 (4.7%) | 33 (3.4%) | 93 (3.2%) | 150 (3.8%) |
| Not for profit | 810 (72.2%) | 1150 (75.2%) | 1303 (77.8%) | 777 (80.0%) | 2281 (77.8%) | 3112 (78.1%) |
| Metropolitan Location | 838 (74.5%) | 1193 (77.9%) | 1347 (80.0%) | 754 (78.2%) | 2356 (80.2%) | 3236 (80.9%) |
| Mean Medicare Past- Year Hospital Procedure Volume (SD) | 10.8 (11.1) | 13.2 (12.6) | 14.9 (14.6) | 11.2 (10.7) | 20.1 (15.8) | 26.0 (21.4) |
| Median Medicare Past- Year Hospital Procedure Volume (IQR) | 6.5 (3–15) | 9 (3–19) | 10 (4–23) | 8 (3–17) | 16 (7–30) | 22 (10–36) |
Abbreviations: SD=standard deviation
Does not include index hospitalization
Changes in Characteristics of Patients with UIAs Undergoing Coiling and Treating Hospitals
Similar to clipping, demographics of patients undergoing coiling did not change over the study period; mean age ranged from 72.4 to 72.5 years, between 78.0% and 80.7% were women, and the proportion of white patients ranged from 88.1% to 90.8% (Table 1). There was also little fluctuation in comorbidity prevalence or in mean Elixhauser comorbidity score over the study period. Between 2001–2003 and 2008–2010, mean past-year Medicare hospital coiling volume more than doubled from 11.2 to 26.0.
Trends in Outcomes Following UIA Clipping or Coiling
Among patients undergoing UIA clipping, 30-day mortality decreased from 3.2% in 2001–2003 to 1.6% in 2008–2010 (Table 2). The length of hospitalization also decreased from a median (IQR) of 6 days (4–11) in 2001–2003 to 5 days (3–8) in 2008–2010. During the index hospitalization, fewer patients died (1.5% vs. 2.6%), had complications (25.0% vs. 28.9%) or were transferred to acute care (1.0% vs. 12.3%) but a greater proportion of patients were transferred to long-term care (44.2% vs. 29.7%) in 2008–2010 than in 2001–2003. Hospital readmissions within 30 days of discharge also decreased over the time period from 18.8% to 14.5%.
Table 2.
Unadjusted Outcome Risks for Medicare Beneficiaries with Unruptured Intracranial Aneurysms Undergoing Clipping or Coiling, 2001–2010
| Clipping | Coiling | |||||||
|---|---|---|---|---|---|---|---|---|
| Outcomes | 2001– 2003 n=1134 % (95% CI) | 2004– 2007 n=1539 % (95% CI) | 2008– 2010 CI) n=1684 % (95% | p- trend | 2001– 2003 n=977 % (95% CI) | 2004– 2007 n=2962 % (95% CI) | 2008– 2010 n=4003 % (95% CI) | p- trend |
| In- hospital mortality | 2.6 (2.1–3.0) | 1.5 (1.1– 1.9) | 1.5 (1.2– 1.9) | 0.076 | 1.5 (1.3–1.8) | 0.8 (0.6–1.0) | 0.7 (0.5–0.9) | 0.048 |
| In- hospital complications* | 28.9 (27.6– 30.3) | 26.4 (25.1– 27.8) | 25.0 (23.7– 26.3) | 0.024 | 17.7 (16.9– 18.5) | 16.4 (15.6– 17.2) | 13.8 (13.1– 14.6) | <.001 |
| Discharge destination† | ||||||||
| Died in hospital | 2.6 (2.1–3.0) | 1.5 (1.1– 1.9) | 1.5 (1.2– 1.9) | 1.5 (1.3–1.8) | 0.8 (0.6–1.0) | 0.7 (0.5–0.9) | ||
| Home | 55.5 (54.0– 56.9) | 53.7 (52.3– 55.2) | 53.3 (51.8– 54.7) | 0.001 | 80.9 (80.1– 81.8) | 83.5 (82.7– 84.3) | 84.0 (83.2– 84.8) | 0.110 |
| Acute care | 12.3 (11.3– 13.2) | 1.4 (1.0– 1.7) | 1.0 (0.7– 1.2) | 3.7 (3.3–4.1) | 0.8 (0.6–1.0) | 0.3 (0.2–0.5) | ||
| Long- term care | 29.7 (28.4– 31.1) | 43.4 (41.9– 44.9) | 44.2 (42.8– 45.7) | 13.8 (13.1– 14.6) | 14.9 (14.1– 15.7) | 15.0 (14.2– 15.8) | ||
| Mean length of stay (SD) | 9.2 (8.7) | 7.8 (8.0) | 7.1 (6.7) | <.001 | 4.6 (6.2) | 3.9 (6.2) | 3.3 (5.0) | <.001 |
| Median (IQR) | 6 (4–11) | 5 (3–9) | 5 (3–8) | <.001 | 2 (1–5) | 2 (1–3) | 2 (1–3) | <.001 |
| 30-day mortality | 3.2 (2.1–4.2) | 1.9 (1.2– 2.6) | 1.6 (1.0– 2.2) | 0.007 | 1.9 (1.1–2.8) | 1.4 (1.0–1.8) | 1.5 (1.1–1.8) | 0.440 |
| 30-day readmission | 18.8 (16.5– 21.2) | 16.6 (14.7– 18.5) | 14.5 (12.8– 16.2) | 0.003 (10.9– 15.2) | 13.0 (10.6–13) | 11.8 (10.0– 12.0) | 11.0 | 0.068 |
Abbreviations: CI=confidence interval; SD=standard deviation; IQR=interquartile range
Includes stroke, hydrocephalus, ventriculostomy, ventricular shunt, tracheotomy, prolonged mechanical ventilation, and post-operative neurological, cardiovascular, or surgical site complications
Discharged against medical advice are considered missing/unknown (<1% of cases)
Outcomes tended to improve for patients undergoing coiling; patients in 2008–2010 had lower risks of 30-day mortality (1.9% vs 1.4%) and in-hospital complications (13.8% vs. 17.7%) than patients in 2001–2003. Compared to 2001–2003, patients in 2008–2010 tended to be increasingly discharged to their home (80.9% vs. 84.0%) and long-term care (13.8% vs. 15.0%) instead of acute care (3.7% vs. 0.3%). While there was no change in median length of stay for the index hospitalization, there was a slight decrease in 30-day readmissions in 2008–2010 compared to 2001–2003 (13.0% vs. 10.9%). Outcome risks were similar for patients aged 66–74 and ≥75 years undergoing clipping or coiling and, over the study period, outcome risks also tended to decrease (supplemental Table IV).
Trends in outcomes of clipping and coiling were consistent when the analysis was repeated by year or two-year blocks.
Trends in Subarachnoid Hemorrhage 2000–2010
Age- and sex-adjusted rates of subarachnoid hemorrhage remained relatively stable at approximately 20 per 100,000 until 2007 (Figure 3). Starting in 2008, the rate of SAH increased to approximately 25 per 100,000 Medicare beneficiaries.
Figure 3.
Age- and Sex-Standardized Rates of Clipping or Coiling and of Subarachnoid Hemorrhage per 100,000 Medicare Beneficiaries, 2000–2010
DISCUSSION
Between 2000 and 2010, the rate of Medicare beneficiaries undergoing procedural treatment for UIA increased several-fold. This increase was driven mainly by the rate of patients undergoing coiling, which increased more than 15-fold between 2000 and 2010. While characteristics of patients with UIA being treated with clipping or coiling did not change substantially, mean past-year Medicare hospital procedural volume increased steadily for clipping and more than doubled for coiling over the study period. Over time, outcomes for patients undergoing both clipping and coiling tended to get better but we did not observe a decrease in SAH rates over the same time period.
Our findings support and advance results of other studies reporting increasing use of UIA clipping and coiling.12–14 One of the factors contributing to the increase in the rate of UIAs being managed through clipping and coiling may be related to increased detection of UIAs. Consistent with this hypothesis is the fact that imaging services reimbursed by Medicare Part B more than doubled from 2000 and 200615 and that, among fee-for-service Medicare beneficiaries, utilization of noninvasive imaging techniques to assess the arterial vasculature of the head such as computer tomography angiography (CTA) and magnetic resonance angiography (MRA) increased by 827% and 39%, respectively, between 2002 and 2007.16 Although routine screening for UIAs is not recommended in the general population,17 the majority of UIAs are discovered incidentally.3,18 Our findings suggest that increased use of imaging techniques in the Medicare population reported previously may be translating into more UIAs being incidentally discovered and subsequently treated.
Our study also suggests that coiling has now become the first-line procedural therapy for patients with UIA if they are eligible for both procedures. This can be at least partially explained by the fact that coiling is considered less physiologically stressful and safer than clipping, as implied by numerous observational studies which have shown that clipping is associated with a higher risk of adverse outcomes.12,13,19–21 The risk of adverse outcomes tended to decrease for both clipping and coiling over time and is likely due to factors including advancements in endovascular techniques,12 general improvements in post-procedural care, and increasing past-year clipping and coiling volumes.22,23 We observed the lowest procedural harms for patients undergoing coiling in 2008–2010, when peri-procedural mortality was 1.4%, non-fatal in-hospital complications risks were 13.8%, 30-day hospital readmissions were 11.0%, and discharge to long-term care was 15.0%. Nevertheless, reductions in peri-procedural morbidity and mortality do not necessarily justify increased preventative UIA treatment. The risk of these events must be weighed against the annual rate of UAI rupture which generally ranges between 0.5% and 1.0%,3–5 but may be much higher depending on size, site, SAH history, aneurysmal symptoms, and smoking status.3–5,24 In addition, the value of procedural treatment must be weighed against life expectancy, which will be lower among Medicare patients than among the general population due to differences in age and comorbidity burden.
Little robust evidence exists that routine UIA treatment results in a net clinical benefit. In this context, the trend we observed in the rate of SAH over the study period is concerning. The primary purpose of preventative UIA clipping and coiling is to reduce the risk of aneurysmal SAH occurrence. However, in spite of the dramatic increase in the rates of procedures, particularly coiling, performed on Medicare beneficiaries with UIAs, the overall rate of SAH among Medicare beneficiaries did not decrease. This is the opposite of what would be expected if procedural treatment of UIAs was preventing aneurysm ruptures that would have occurred without treatment. Therefore, it is reasonable to suspect that for some patients in this age group, the value of clipping or coiling their UIAs is either modest or non-existent, particularly in light of procedural complications and the effect of procedure-associated morbidity and hospitalizations on quality of life.
The results of this study must be interpreted in the context of certain limitations. We were not able to investigate long-term outcome risks such as aneurysm recurrence and we did not have post-procedural information on the modified Rankin Scale Score or other measures of dependency. Although discharge to long-term care is likely a good proxy for functional disability, the expected benefits of preventive clipping and coiling need to be weighed against other factors affecting survival and quality of life that were not measured in this study. We observed non-decreasing SAH rates but could not determine whether it was due to UIA treatment complications (which appeared to be decreasing), aneurysm recurrence, limited life expectancy, insufficient study follow-up time, or another mechanism. Lastly, we did not have information on size, stability, and location of UIAs and could not determine if and how the selection of treated UIAs changed over time nor whether outcomes for UIAs with certain characteristics improved more so than others.
There are several implications of our study. First, we believe the main question for preventative UIA treatment may be not whether coiling is better than clipping but rather what level of risk, if any, is justified. In this study, we did not observe a decrease in SAH rates as clipping and coiling rates increased. Since the risk of rupture is low, it may be that some patients do not live long enough to benefit from the primary purpose of the procedure: SAH prevention. Second, we found that patients between the ages of 65 to 74 years tended to have greater increases in the rates of clipping and coiling over the study period, which likely reflects the selection of patients most likely to benefit from preventative UIA treatment. Further studies should further aid providers in identifying Medicare beneficiaries who are most likely to benefit from preventative UIA treatment, given the possibility for significant competing risks, peri-procedural complication risks, and low rates of rupture. Finally, randomized clinical trials and real-world observational studies comparing the different treatment modalities for UIA, including conservative management, are also needed to determine the optimal management strategy for UIA, particularly in older adults.
Supplementary Material
Acknowledgments
None
Sources of Funding: Dr. Kamel is supported by grant K23NS082367 from National Institutes of Health (NIH)/National Institute of Neurological Disorders and Stroke (NINDS).
Footnotes
Disclosures: The authors have no relevant conflicts of interest. Art Sedrakyan received funding from the Food and Drug Administration (FDA) for establishing the Medical Device Epidemiology Network (MDEpiNet) Science and Infrastructure Center.
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