Prediction model for 3-year rupture risk of unruptured cerebral aneurysms in Japanese patients

OBJECTIVE

To build a prediction model that estimates the 3-year rupture risk of unruptured saccular cerebral aneurysms.

METHODS

Survival analysis was done using each aneurysm as the unit for analysis. Derivation data were from the Unruptured Cerebral Aneurysm Study (UCAS) in Japan. It consists of patients with unruptured cerebral aneurysms enrolled between 2000 and 2004 at neurosurgical departments at tertiary care hospitals in Japan. The model was presented as a scoring system, and aneurysms were classified into 4 risk grades by predicted 3-year rupture risk: I, < 1%; II, 1 to 3%; III, 3 to 9%, and IV, >9%. The discrimination property and calibration plot of the model were evaluated with external validation data. They were a combination of 3 Japanese cohort studies: UCAS II, the Small Unruptured Intracranial Aneurysm Verification study, and the study at Jikei University School of Medicine.

RESULTS

The derivation data include 6,606 unruptured cerebral aneurysms in 5,651 patients. During the 11,482 aneurysm-year follow-up period, 107 ruptures were observed. The predictors chosen for the scoring system were patient age, sex, and hypertension, along with aneurysm size, location, and the presence of a daughter sac. The 3-year risk of rupture ranged from <1% to >15% depending on the individual characteristics of patients and aneurysms. External validation indicated good discrimination and calibration properties.

INTERPRETATION

A simple scoring system that only needs easily available patient and aneurysmal information was constructed. This can be used in clinical decision making regarding management of unruptured cerebral aneurysms.

The clinical decision analysis using decision tree

The clinical decision analysis (CDA) has used to overcome complexity and uncertainty in medical problems. The CDA is a tool allowing decision-makers to apply evidence-based medicine to make objective clinical decisions when faced with complex situations. The usefulness and limitation including six steps in conducting CDA were reviewed. The application of CDA results should be done under shared decision with patients' value.

Cost-effectiveness of treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage

RATIONALE AND OBJECTIVES

The study goal was to evaluate the cost-effectiveness of surgery and endovascular treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage from a previous aneurysm, incorporating the results of the prospective International Study of Unruptured Intracranial Aneurysms.

MATERIALS AND METHODS

Using a Markov model, we performed a decision and cost-effectiveness analysis comparing surgery or endovascular treatment with no treatment. Twelve clinical scenarios were defined based on aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year.

RESULTS

In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms less than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7- to 24-mm aneurysms, whereas surgery was the most cost-effective option for aneurysms of 25 mm or larger. For aneurysms less than 7 mm and located in the posterior circulation, endovascular treatment was the most cost-effective option, whereas surgery was the most cost-effective option for 7- to 12-mm aneurysms. No treatment was the most cost-effective strategy for aneurysms of 13 mm or larger.

CONCLUSION

For 50-year-old patients with a history of aneurysmal subarachnoid hemorrhage, treatment of unruptured aneurysms that are located in the cavernous carotid artery, or small (<7 mm) and located in the anterior circulation, or large (>or=13 mm) and located in the posterior circulation is ineffective or not cost-effective.

Screening for familial intracranial aneurysms: decision and cost-effectiveness analysis

RATIONALE AND OBJECTIVES

To evaluate the potential benefits, harms, and cost-effectiveness of screening for asymptomatic, unruptured intracranial aneurysms in family members of patients with aneurysmal subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

Using a Markov model, we performed a decision and cost-effectiveness analysis comparing magnetic resonance (MR) angiography screening for asymptomatic, unruptured intracranial aneurysms to no screening in family members of patients with aneurysmal SAH. Treatment of unruptured intracranial aneurysms was determined according to patient age and aneurysm size and location. Cohort age was taken as 40 years.

RESULTS

In family members with two or more affected first-degree relatives, screening compared with no screening had an incremental cost-effectiveness ratio (ICER) of $37,400 per quality-adjusted life-year (QALY). With screening, life expectancy increased from 39.44 years to 39.55 years. The ICER of screening was >$50,000 per QALY if age at screening was > or =50 years. In family members with one affected first-degree relative, screening compared with no screening had an ICER of $56,500 per QALY.

CONCLUSIONS

The results suggest that MR angiography screening for asymptomatic, unruptured intracranial aneurysms in family members with two or more affected first-degree relatives is cost-effective. The benefit and cost-effectiveness are dependent on age at screening.

Completion angiography for surgically treated cerebral aneurysms: an economic analysis

OBJECTIVE

To compare cost-effectiveness of different strategies for completion angiography after cerebral aneurysm clipping.

METHODS

A literature search was used to determine the outcome probabilities and costs of various strategies. The pooled results were used in a Markov cost-effectiveness model to compare quality-adjusted life-years and costs of each strategy. Sensitivity (threshold) analyses and Monte Carlo simulation were used to test variation in the model.

RESULTS

Routine (for all cases) intraoperative angiography proved to be slightly more cost-effective than selective (only for cases deemed "high risk") intraoperative angiography, being both less costly and more effective. Routine postoperative angiography was the least cost-effective. However, in centers whose rates of clip-induced arterial compromise are much lower than the averages reported in the literature, selective angiography might be warranted.

CONCLUSION

Routine intraoperative angiography remains the most cost-effective form of completion angiography after aneurysm clipping, at least at our present state of technology.

Treatment of unruptured intracranial aneurysms: decision and cost-effectiveness analysis

PURPOSE

To prospectively perform a decision and cost-effectiveness analysis of surgical and endovascular treatments of unruptured intracranial aneurysms, with incorporation of the results of the prospective International Study of Unruptured Intracranial Aneurysms.

MATERIALS AND METHODS

With use of a Markov model, a decision and cost-effectiveness analysis was performed for comparison of surgical or endovascular treatment with no treatment. Twelve clinical scenarios were defined on the basis of aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old patient cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year.

RESULTS

In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms smaller than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7-24-mm aneurysms, whereas surgical treatment was the most cost-effective option for aneurysms 25 mm or larger. For aneurysms smaller than 7 mm or 25 mm or larger located in the posterior circulation, no treatment was the most cost-effective strategy. Surgical treatment was the most cost-effective option for 7-12-mm aneurysms, whereas endovascular treatment was the most cost-effective option for 13-24-mm aneurysms.

CONCLUSION

For 50-year-old patients, treatment of aneurysms that are small (<7 mm), that are located in the cavernous carotid artery, or that are large (>or=25 mm) and located in the posterior circulation is ineffective or not cost-effective.

A probabilistic and interactive decision-analysis system for unruptured intracranial aneurysms

OBJECT

The goal in this study was to develop an interactive, probabilistic decision-analysis system for clinical use in the decision to treat or observe unruptured intracranial aneurysms. Further goals were to enable users of the system to adapt decision-analysis methods to individual patients and to provide a tool for interactive sensitivity analysis.

METHODS

A computer program was designed to model the outcomes of treatment and observation of unruptured aneurysms. The user supplies probabilistic estimates of key parameters relating to a specific patient and nominates discount rate and quality of life adjustments. The program uses Monte Carlo discrete-event simulation methods to derive probability estimates of the outcomes of treatment and observation. Results are expressed as summary statistics and graphs. Discounted quality-adjusted life years are graphed using survival methods. Hierarchical simulations are used to enable investigators to perform probabilistic sensitivity analysis for one or multiple parameters simultaneously. The results of sensitivity analysis are expressed in graphs and as the expected value of perfect information. The system can be distributed and updated using the Internet.

CONCLUSIONS

Further research is required into the benefits of clinical application of this system. Further research is also required into the optimum level of complexity of the model, into the user interface, and into how clinicians and patients are likely to interpret results. The system is easily adaptable to a range of medical decision analyses.

Impact of Surgical Clipping on Survival in Unruptured and Ruptured Cerebral Aneurysms

Background and Purpose— The management of aneurysms is controversial because little is known about the impact of clipping on long-term outcome. This study was designed to evaluate long-term survival of patients with aneurysms undergoing clipping in a statewide population.

Methods— We used a retrospective design using an administrative database to identify patients hospitalized with aneurysms (1987 to 2001). Time-to-event analysis was used to determine the risk of death from all causes and from neurological causes.

Results— 4619 patients (mean age 54.7±15.3, 66.3% female) were hospitalized with cerebral aneurysms. Survival among patients with ruptures was significantly lower compared with patients with unruptured aneurysm ( P <0.001) with adjusted hazard ratio (HR) of death after clipping 40% higher (HR: 1.4; 95% CI: 1.2, 1.7) in patients with rupture compared with those that were unruptured. Survival estimates for unruptured patients who underwent clipping were significantly higher than among those unruptured patients who did not undergo clipping ( P <0.001), with adjusted HR of death 30% higher in patients with unruptured aneurysm that were not clipped compared with unruptured patients who were clipped (HR: 1.3; 95% CI: 1.1, 1.6). Patients with unruptured aneurysm who underwent clipping and survived beyond the 30-day postoperative period were less likely to die from neurologically related causes (5.6 versus 2.3%, P <0.001). Patients with ruptures and aneurysms who underwent clipping have a higher rate of death compared with the general population in the long-term.

Conclusions— Short-term and long-term mortality after clipping of cerebral aneurysms is higher than previously reported. Patients with unruptured aneurysms who undergo clipping have improved survival compared with those who do not undergo clipping. This study supports the use of early intervention in the management of patients with unruptured aneurysms.

Cost-effectiveness analysis of telemedicine to evaluate diabetic retinopathy in a prison population

OBJECTIVE

A cost-effectiveness analysis was conducted to investigate the clinical and economic impact of teleophthalmology in evaluating diabetic retinopathy in prison inmates with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Based on a hypothetical teleophthalmology system to evaluate diabetic retinopathy patients with type 2 diabetes in a prison care setting, a Markov decision model was developed with probability and cost data derived primarily from published epidemiological and outcome studies. A 40-year-old African-American man with type 2 diabetes was used as a reference case subject. The number of quality-adjusted life-years (QALYs) gained was used as the clinical outcome, and the cost in U.S. dollars from the year 2003 was used as the economic outcome. Teleophthalmology and nonteleophthalmology strategies were compared using an expected QALYs calculation and two types of sensitivity analyses: probabilistic and traditional n-way sensitivity analyses.

RESULTS

The teleophthalmology strategy dominates in the cost-effectiveness analysis for the reference case subject: 16,514/18.73 dollars QALYs for teleophthalmology and 17,590/18.58 dollars QALYs for nonteleophthalmology. Ninety percent of the Monte Carlo simulations showed cost effectiveness (annual cost/QALYs < or = 50,000 dollars) in the teleophthalmology strategy based on an assumed inmate population. Teleophthalmology is the better strategy if the number of diabetic inmates in the prison community is >500.

CONCLUSIONS

Our cost-effectiveness analysis demonstrates that teleophthalmology holds great promise to reduce the cost of inmate care and reduce blindness caused by diabetic retinopathy in type 2 diabetic patients.