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PubMed1997

Life table analysis of pregnancy rates in women with moderate or severe endometriosis comparing danazol therapy after carbon dioxide laser laparoscopy plus electrocoagulation or laparotomy plus electrocoagulation versus danazol therapy only.

STUDY OBJECTIVE: To assess the effectiveness, in terms of pregnancy rates, of isotopic 13CO2 laser laparoscopy versus traditional laparoscopy or laparotomy in the treatment of infertile women with moderate or severe endometriosis. DESIGN: Prospective 5-year study. SETTING: Medical school-affiliated hospital. PATIENTS: Three hundred nine infertile women with moderate to severe endometriosis. INTERVENTIONS: The patients were treated with one of four options: operative laparoscopy with the 13carbon dioxide (13CO2) laser vaporization and/or resection, operative laparoscopy with simple electrocoagulation and sharp dissection, laparotomy with electrocoagulation and sharp dissection, and medical treatment with danazol. Estimated cumulative pregnancy rates using life table analyses were indicators of treatment of success and compared among treatments. A subgroup of 192 women considered to have endometriosis as the only infertility factor was also evaluated. MEASUREMENTS AND MAIN RESULTS: Pregnancy rates in the laparoscopy group were equal to or higher than those of the laparotomy group, for both the entire population and the endometriosis-only subset. When the CO2 laser was used as an adjuvant option, the rates were better, especially in patients with advanced disease and with endometriosis as the only infertility factor. CONCLUSION: In women with endometriosis as the only infertility factor, laparoscopic surgery with the 13CO2 laser was more effective than nonlaser treatment.

Adult↗
PubMed2006

Dental implants placement in conjunction with osteotome sinus floor elevation: a 12-year life-table analysis from a prospective study on 588 ITI implants.

OBJECTIVES: The purpose of this prospective study was to evaluate the clinical success of placing ITI dental implants in the posterior maxilla using the osteotome technique. MATERIAL AND METHODS: All implants were placed following a one-stage protocol (elevating the sinus floor and placing the implant at the same time). Five hundred and eighty-eight implants were placed in 323 consecutive patients with a residual vertical height of bone under the sinus ranging from 6 to 9 mm. The mean observation follow-up period was 59.7 months (with a range of 12-144 months). This prospective study not only calculated the 12-year cumulative survival and success rates for 588 implants by life-table analysis but also the cumulative success rates for implant subgroups divided per implant length and the percentage of sinus membrane perforation were evaluated. RESULTS: The 12-year cumulative survival and success rates were 94.8% and 90.8%, respectively. The analysis of implant subgroups showed slightly more favourable cumulative success rates for 12 mm long implants (93.4%) compared with 10 and 8 mm long implants (90.5% and 88.9%, respectively). During the study period, only 13 perforations of the Schneiderian membrane were detected with a perforation rate of 2.2% (13 perforations/601 treated sites). Ten perforations out of 13 were caused during the first half of the study period and of these, seven were detected during the first 3 years of this prospective study. CONCLUSION: Based on the results and within the limits of the present study, it can be concluded that ITI implant placement in conjunction with osteotome sinus floor elevation represents a safe modality of treating the posterior maxilla in areas with reduced bone height subjacent to the sinus as survival and success rates were maintained above 90% for a mean observation period of approximately 60 months. Shorter implants (8 mm implants) did not significantly fail more than longer ones (10 and 12 mm implants): the differences were small compared with the number of events; hence, no statistical conclusion could be drawn. But, from the clinical point of view, the predictable use of short implants in conjunction with osteotome sinus floor elevation may reduce the indication for complex invasive procedures like sinus lift and bone grafting procedures.

Adult↗
PubMed2001

Life-table analysis of the risk of perinatal death at term and post term in singleton pregnancies.

OBJECTIVE: This study was undertaken to estimate the cumulative risk of perinatal death associated with delivery at each gestational week both at term and post term. STUDY DESIGN: The numbers of antepartum stillbirths, intrapartum stillbirths, neonatal deaths, and surviving neonates delivered at between 37 and 43 weeks' gestation in Scotland, 1985-1996, were obtained from national databases (n = 700,878) after exclusion of multiple pregnancies and deaths caused by congenital abnormality. The numbers of deaths at each gestational week were related to appropriate denominators: antepartum stillbirths were related to ongoing pregnancies, intrapartum stillbirths were related to all births (excluding antepartum stillbirths), and neonatal deaths were related to live births. The cumulative probability of perinatal death associated with delivery at each gestational week was estimated by means of life-table analysis. RESULTS: The gestational week of delivery associated with the lowest cumulative risk of perinatal death was 38 weeks' gestation, whereas the perinatal mortality rate was lowest at 41 weeks' gestation. The risk of death increased more sharply among primigravid women after 38 weeks' gestation because of a greater risk of antepartum stillbirth. The relationships between risk of death and gestational age were similar for the periods 1985-1990 and 1991-1996. CONCLUSION: Delivery at 38 weeks' gestation was associated with the lowest risk of perinatal death.

Female↗
PubMed1984

Use of the life table to eliminate from the active record Hansen's disease patients out of control and of unknown whereabouts: a six-year experience using this method in the state of Rio Grande do Sul.

Three criteria for the withdrawal of Hansen's disease patients of unknown whereabouts from the active record are presented, based on patients' age, number of years they have been out of control, and probability of their being alive, calculated according to a regional mortality table. In the first criterion, patients who have been lost and who according to their life table have a lower than 50% mathematical probability of being alive were given "statistical discharge." In the second and third criteria, Mitsuda-negative patients who had been lost for more than 20 years and Mitsuda-positive patients who had been lost for more than ten years and who had not been included in the first criterion were given "statistical discharge." During the six years in which the method was used in the state of Rio Grande do Sul, Brazil, 506 patients of unknown whereabouts were withdrawn from the active record, four of whom were found to be alive with the disease in progress. The results that have been achieved suggest an accuracy rate of about 100% for the first criterion of "statistical discharge" and about 98% for the other two criteria.

Actuarial Analysis↗
PubMed2002

Long-term clinical effectiveness of oral implants in the treatment of partial edentulism. Seven-year life table analysis of a prospective study with ITI dental implants system used for single-tooth restorations.

One hundred and eight-seven ITI implants were prospectively followed from November 1992 to July 2000, in order to evaluate the clinical efficiency and the long-term prognosis in 109 partially edentulous patients (69 women and 40 men; average age 41.3 years). Of these 187 implants, 69.5% were placed in the mandible and 30.5% in the maxilla. After a healing period that ranged from three to six months, the osseointegrated implants (n = 184) were restored with single crowns. Three implants were extracted prior to loading the fixture and were considered early failures. Each implant was reassessed on a yearly basis, both clinically and radiographically. The results of the investigation, which were evaluated according to predefined success criteria, were reviewed in accordance with a life table method. During the follow-up, six cases were deemed to be late failures. In each of these cases, a suppurative infection of the peri-implant tissue was diagnosed: in one implant, the infection could not be eradicated and the implant was removed. When 11 drop-outs were included in the analysis, the cumulative survival and success rates for the whole sample group were 96.77% and 93.6%, respectively. When only prosthetically loaded implants were considered, the results increased to 99.35% for the cumulative survival rate and 96.18% for the cumulative success rate. The analysis on disaggregated data showed better results for maxillary restorations (survival rate 100%) in comparison to mandible restorations (survival rate 95.11%). It was concluded that, under standard anatomic conditions (bone site height > 8 mm, thickness > 6 mm), prosthetic restoration of partially edentulous patients with the ITI system can be described as a reliable and efficient therapy in the long term.

Adult↗
PubMedDate not supplied

Life table analysis and clinical evaluation of oral implants supporting prostheses after resection of malignant tumors.

Seventeen mostly elderly patients, 13 men and 4 women, were consecutively admitted for implant-prosthodontic treatment after they had undergone resection of malignant tumors in the oral cavity. A total of 53 dental implants (ITI-Straumann) was placed, 12 in the maxilla, 41 in the mandible. The prosthetic rehabilitation consisted of overdenture therapy in 15 patients, and 2 patients were treated with fixed partial prostheses. Thirty-three implants were prescribed for patients who received radiotherapy either before or after implant placement. The average dose varied between 50 and 74 Gy. Eighteen implants were located in grafted bone from the fibula, scapula, or hip. For 2 patients, hyperbaric oxygen therapy was also prescribed after osteoradionecrosis had developed. One implant was lost before prosthetic loading. During an observation period of up to 7 years after loading, 3 more implants were removed. All implant losses occurred in the mandibles of patients who had received radiotherapy. A life table analysis was performed, and the cumulative survival rates, calculated for 2, 3, and 5 years, were 93%, 90%, and 90% respectively. No failures or complications were observed with technical components of the implants or prostheses. All prostheses could be maintained during the entire observation time. Although in the present investigation the survival rate of implants was slightly lower than under standard conditions, the treatment with implant-supported prostheses seemed to be advantageous for patients who had undergone intraoral resections.

Adult↗
PubMed2002

The evolution of Z stent-based stent-grafts for endovascular aneurysm repair: a life-table analysis of 7.5-year followup.

BACKGROUND: The purpose of this study was to analyze the impact of stent-graft design and operator skills on outcomes after endovascular abdominal aortic aneurysm repair. STUDY DESIGN: One hundred sixty-four patients (mean age 71 years) underwent stent-graft repair. Patients were treated with four different types of stent-graft: first-generation (n = 58) and second-generation (n = 17) Ivancev-Malmö monoiliac stent-grafts (IM I and IM II, respectively) combined with femoral-femoral crossover, Chuter bifurcated stent-graft (n = 15), and the Zenith stent-graft (n = 74). Patients underwent digital subtraction angiography and contrast CT preoperatively and were then followed with CT scans postoperatively. Recently, followup was changed to CT scanning at 1 month and 1 year postoperatively and annually thereafter. Ultrasonographic duplex scanning substitutes in the remaining followup. Changes in aneurysm diameters and occurrence of endoleaks were recorded. Short- and midterm mortality and complications and postoperative secondary interventions were recorded, and life-table analysis for intervention-free stent-graft survival was calculated. RESULTS: Immediate and late conversions and 30-day mortality were reduced for second- (IM II and Zenith) compared with first-generation stent-grafts (IM I and Chuter). Stent-graft migrations occurred only with the IM I and Chuter stent-grafts. Type I endoleak was significantly more common in first-generation stent-grafts. First-generation stent-grafts required significantly more secondary interventions than second-generation stent-grafts up to 30 months postoperatively. CONCLUSION: Enhanced stent-graft design has improved the probability of stent-graft success after endovascular abdominal aortic aneurysm repair. Better technical skills and increased use of intraoperative adjunctive procedures may also have contributed to improved results.

Aged↗
PubMedDate not supplied

Life-table analysis of cyclosporin A treatment in psoriatic arthritis: comparison with other disease-modifying antirheumatic drugs.

OBJECTIVES: The aim of this study was to determine the cumulative probability of taking CsA in comparison to other DMARDs, as well as the reason for discontinuation of each DMARD, in a large cohort of PsA patients. METHODS: We prospectively studied 172 consecutive patients with a diagnosis of PsA who had been admitted to our rheumatological unit since 1984. We collected information about treatment with DMARDs including: number, dose, duration and causes of withdrawal, including side effects or inefficacy. Cumulative survival analysis was performed by the Kaplan-Meier test and the differences between these survival curves were determined by the Mantel-Hanszel test. RESULTS: The probability curve of continuing to take CsA was significantly lower than that of MTX (p < 0.046). The rate of adverse effects responsible for stopping DMARD therapy was higher in the CsA group, especially with respect to the antimalarial group (p < 0.014). The most common cause of CsA withdrawal was hypertension. The rate of withdrawal due to inefficacy in the CsA group was not significantly different from those observed in the other groups. Nevertheless, the total frequency of discontinuation due to toxicity and inefficacy in the MTX group was significantly lower compared to the gold salts (p < 0.05) and CsA groups (p < 0.01). CONCLUSION: Life-table analysis suggests that PsA patients taking CsA are less likely than patients on MTX to continue long term treatment. Therefore CsA, which seems to be less safe than the antimalarials, could be considered a useful drug in the treatment of PsA, but does seem to represent the drug of first choice, particularly when compared to MTX.

Adolescent↗
PubMed2001

Improved survival after endoluminal repair with second-generation prostheses compared with open repair in the treatment of abdominal aortic aneurysms: a 5-year concurrent comparison using life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by means of open repair (OR) and endoluminal repair (ER) with second-generation prostheses by the same surgeons during a defined interval. METHODS: Between May 1995 and December 1998 second-generation (low profile, fully supported, modular) endoprostheses were implanted in 148 patients. These patients, together with 135 patients treated concurrently with OR during the same period, comprised the study group of 283 patients. Patient selection was based on aneurysm morphology. Those patients who were anatomically suitable for ER were treated with this method. The ER and OR groups were similar with regard to age, sex, and size of AAA. The ER group contained high-risk patients considered unfit for OR (n = 46), and the OR group contained high-risk patients who were anatomically unsuitable for ER (n = 19). Outcome criteria in both groups were survival and successful aneurysm repair. Success in the ER group was defined as exclusion of the aneurysm sac and stability or reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, regardless of whether they were subsequently corrected with secondary endovascular intervention. Data were analyzed with the life table method. The minimum period of follow-up for all patients was 18 months. RESULTS: The perioperative mortality rate was 5.9% in the OR group and 2.7% in the ER group (not significant). There was a statistically significant difference between the survival curves of the two groups in favor of the ER group when analyzed with the log-rank test (P =.004). The Kaplan-Meier curve for graft failure for the ER group revealed a 3-year graft success probability of 82%. Survival probability with successful repair in the OR group at 3 years was 85%. CONCLUSIONS: A concurrent comparison of ER with second-generation prostheses versus OR demonstrated a significant difference in survival in favor of the ER group. The probability of survival with successful repair at 3 years was similar in both groups.

Aged↗
PubMedDate not supplied

Long-term evaluation of submerged and nonsubmerged ITI solid-screw titanium implants: a 10-year life table analysis of 468 implants.

PURPOSE: Submerged and nonsubmerged ITI solid-screw titanium implants were followed retrospectively from 1989 to 1993 and prospectively from 1994 on to analyze long-term prognosis in partially and fully edentulous patients. MATERIAL AND METHODS: A total of 468 implants were consecutively inserted in 191 patients from 1989 to 1998. Two hundred twenty-eight successfully integrated fixed-restoration implants and 238 with removable restorations were restored following a healing period of 4 to 6 months (9 months in sinus floor elevation sites). From 1994 on all implants inserted were documented annually up to 9 years. During examination the clinical status of the implants was analyzed and evaluated according to predefined criteria of success and this allowed the calculation of 10-year cumulative survival and success rates for 468 implants. RESULTS: Two implants (0.43%) did not successfully integrate during the healing period, and 8 implants (1.7%) were classified as failures during follow-up (1 late failure under load, 7 with a progressive bone loss from 1 to 3 threads). Including 68 implants in subjects who dropped out (with a dropout rate of 14.4%), the 10-year cumulative survival and success rates were 99.2% and 96.4%, respectively. DISCUSSION: Over the course of this long-term study, osseointegrated implants, once used as a last possible solution, became nearly standard in cases of single-tooth implants because of the high rate of long-term success. Life table analysis not only determines whether an implant is functioning, it also makes a statement about its clinical status according to strict success criteria. CONCLUSION: The study demonstrated that ITI solid-screw titanium implants achieved success rates above 95% in a clinical center for an observation period of up to 10 years.

Adolescent↗
PubMed1998

Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method.

AIM: The aim of this study was to determine the influence of graft configuration on the outcome of endoluminal repair of abdominal aortic aneurysm (AAA). METHODS: The 5-year study period extended from May 1992 to May 1997 and included analysis of patients undergoing endoluminal AAA repair in the first 4.5-year period with a minimum follow-up period of 6 months. Between May 1992 and November 1996 136 patients underwent endoluminal AAA repair. Two patients who had endoluminal repair of anastomotic AAA and six patients who had secondary endoluminal repair of AAA were excluded, leaving 128 patients in the study group. There were 117 males and 11 females with a mean age for the group of 71 years. The configuration of the grafts was tubular aortic (T) (n = 50), tapered aortoiliac/femoral (AI) (n = 24) and bifurcated (B) (n = 54). Patient characteristics and co-morbidities were similar in the three groups. The procedures were performed in the operating room under radiographic control. Follow-up was complete and consisted of regular physical examination and contrast enhanced computed tomography. Outcome measures were perioperative mortality rate, need for conversion to open repair, presence of early and late endoleaks, successful exclusion of AAA from the circulation, and survival. Data were analysed by the life table method. RESULTS: There was no significant difference in perioperative mortality for T (4%), AI (4%) and B (5.5%) configuration of endograft. Outcome for T, AI, and B configurations was respectively: primary conversion (%) 8, 12, 13; early endoleaks (n =) 5, 0, 1; late endoleaks (n =) 7, 0, 1. The overall incidence of failed procedures throughout the study period was higher in tube grafts compared with non-tube (aortoiliac and bifurcated) grafts (p < 0.05). Kaplan-Meier curves demonstrated a success probability at 40 months of 50% for tube grafts and 80% for non-tube grafts. However, a comparison of the time to procedure failure between tube versus non-tube after adjusting for competing risks (death without prior graft failure) was non-significant (p = 0.14). CONCLUSIONS: The poor mid-term outcome for tube prostheses requires a reassessment of the criteria for selecting this configuration. It would be unwise to abandon the use of tube prostheses entirely in endoluminal repair. With increasing information on mid and long-term outcome of endoluminal AAA repair it is likely that there will be an increasing acceptance of treating smaller AAA while they are still suitable for treatment by the endoluminal method and most likely with tube grafts. A tightening of the criteria for using tube prostheses would seem sensible. In particular, the minimum length of distal neck required for endoluminal tube graft repair should be increased to the 2-2.5 cm range.

Aged↗
PubMed2000

Comparison of first- and second-generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis.

PURPOSE: The outcome of endoluminal repair of abdominal aortic aneurysms with two generations of prostheses was analyzed and compared. METHODS: Between May 1992 and December 1998, 266 patients underwent elective endoluminal repair of an AAA. First-generation prostheses were used in 118 patients (group I), and second-generation prostheses were used in 148 patients (group II). The two groups were similar in age, sex, and size of AAA. The proportion of patients with comorbidities was higher in group I than in group II, but not significantly. First-generation devices were characterized by large (24F internal diameter) delivery systems, one-piece construction, and a lack of metallic support throughout their length. Second-generation devices had smaller (21F or smaller internal diameter) delivery systems, modular construction, and a metallic frame throughout the length of the prostheses. The major end-point criteria were survival and successful endoluminal repair. Success was defined as the exclusion of the aneurysm sac from the circulation, with stability or the reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, irrespective of whether they were subsequently corrected by means of secondary endovascular intervention. The minimum follow-up period was 5 months for each of the 266 patients. Analysis was performed by means of the life-table method. RESULTS: Perioperative mortality was not significantly different between group I (4.2%) and group II (2.7%). There was a statistically significant difference between the survival curves of the two generations, which favored group II (P =.012). There was a significant (P <.001) difference between the two generations of patients in their conditional probability of graft failure when the competing risk of all-cause mortality was considered. Second-generation patients were at a lower risk of graft failure than first-generation patients. The probability of failure, expressed as a proportion of grafts failing at 2 years, was 0.15 for patients with second-generation prostheses and 0.33 for patients with first-generation prostheses. CONCLUSION: Endoluminal AAA repair is a safe procedure, whether first- or second-generation prostheses are used. Survival and probability of graft success were significantly higher with second-generation prostheses than with first-generation prostheses. This improvement in outcome resulted from a combination of increasing clinical experience and advances in technology. A more accurate evaluation of the role of the endoluminal method in AAA repair would be achieved by studying patients in whom second-generation devices were used, rather than longer term studies in which first- and second-generation devices were used.

Aged↗
PubMed1997

Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multi-center study with 2359 implants.

In the present multi-center study, non-submerged ITI implants were prospectively followed to evaluate their long-term prognosis in fully and partially edentulous patients. In a total of 1003 patients, 2359 implants were consecutively inserted. Following a healing period of 3-6 months, the successfully integrated implants were restored with 393 removable and 758 fixed restorations. Subsequently, all consecutive implants were documented annually up to 8 years. At each examination, the clinical status of all implants was evaluated according to predefined criteria of success. Therefore, the data base allowed the evaluation of 8-year cumulative survival and success rates for 2359 implants. In addition, cumulative success rates were calculated for implant subgroups divided per implant type, implant length, and implant location. Furthermore, the actual 5-year survival and success rates could be determined for 488 implants. During the healing period, 13 implants did not successfully integrate, whereas 2346 implants fulfilled the predefined criteria of success. This corresponds with an early failure rate of 0.55%. During follow-up, 19 implants were classified as failures due to several reasons. In addition, 17 implants (approximately 0.8%) demonstrated at the last annual examination a suppurative periimplant infection. Including 127 drop out implants (= 5.4% drop out rate) into the calculation, the 8-year cumulative survival and success rates resulted in 96.7% and 93.3%, respectively. The analysis of implant subgroups showed slightly more favorable cumulative success rates for screw type implants (> 95%) compared to hollow-cylinder implants (91.3%), and clearly better success rates for mandibular implants (approximately 95%) when compared to maxillary implants (approximately 87%). The actual 5-year survival and success rates of 488 implants with 98.2% and 97.3%, respectively, were slightly better than the estimated 5-year cumulative survival and success rates of 2359 implants indicating that the applied life table analysis is a reliable statistical method to evaluate the long-term prognosis of dental implants. It can be concluded that non-submerged ITI implants maintain success rates well above 90% in different clinical centers for observation periods up to 8 years.

Adolescent↗
PubMed2003

In-stent recurrent stenosis after carotid artery stenting: life table analysis and clinical relevance.

OBJECTIVES: Carotid artery stenting has been proposed as an alternative to carotid endarterectomy in cerebral revascularization. Although early results from several centers have been encouraging, concerns remain regarding long-term durability of carotid artery stenting. We report the incidence, characteristics, and management of in-stent recurrent stenosis after long-term follow-up of carotid artery stenting. METHODS: Carotid artery stenting (n = 122) was performed in 118 patients between September 1996 and March 2003. Indications included recurrent stenosis after previous carotid endarterectomy (66%), primary lesions in patients at high-risk (29%), and previous ipsilateral cervical radiation therapy (5%). Fifty-five percent of patients had asymptomatic stenosis; 45% had symptomatic lesions. Each patient was followed up with serial duplex ultrasound scanning. Selective angiography and repeat intervention were performed when duplex ultrasound scans demonstrated 80% or greater in-stent recurrent stenosis. Data were prospectively recorded, and were statistically analyzed with the Kaplan-Meier method and log-rank test. RESULTS: Carotid artery stenting was performed successfully in all cases, with the WallStent or Acculink carotid stent. Thirty-day stroke and death rate was 3.3%, attributable to retinal infarction (n = 1), hemispheric stroke (n = 1), and death (n = 2). Over follow-up of 1 to 74 months (mean, 18.8 months), 22 patients had in-stent recurrent stenosis (40%-59%, n = 11; 60%-79%, n = 6; > or =80%, n = 5), which occurred within 18 months of carotid artery stenting in 13 patients (60%). None of the patients with in-stent recurrent stenosis exhibited neurologic symptoms. Life table analysis and Kaplan-Meier curves predicted cumulative in-stent recurrent stenosis 80% or greater in 6.4% of patients at 60 months. Three of five in-stent recurrent stenoses occurred within 15 months of carotid artery stenting, and one each occurred at 20 and 47 months, respectively. Repeat angioplasty was performed once in 3 patients and three times in 1 patient, and repeat stenting in 1 patient, without complications. One of these patients demonstrated asymptomatic internal carotid artery occlusion 1 year after repeat intervention. CONCLUSIONS: Carotid artery stenting can be performed with a low incidence of periprocedural complications. The cumulative incidence of clinically significant in-stent recurrent stenosis (> or =80%) over 5 years is low (6.4%). In-stent restenosis was not associated with neurologic symptoms in the 5 patients noted in this cohort. Most instances of in-stent recurrent stenosis occur early after carotid artery stenting, and can be managed successfully with endovascular techniques.

Aged↗
PubMed1998

Concurrent comparison of endoluminal versus open repair in the treatment of abdominal aortic aneurysms: analysis of 303 patients by life table method.

PURPOSE: The aim of this study was to compare the outcome of consecutive patients with abdominal aortic aneurysm (AAA) treated concurrently by open operation and endoluminal intervention by the same surgeons during a defined interval. METHODS: Between May 1992 and May 1996, 362 consecutive patients with AAA underwent repair. Fifty-three patients who underwent open operations for ruptured AAA plus two patients who underwent endoluminal repair of false AAA and four patients who underwent secondary endoluminal repair of AAA were excluded, leaving 303 patients who underwent elective repair of true AAA in the study. The elective operations were conventional open repair (OR) in 195 patients (151 men, 44 women; mean age, 69 years) and endoluminal repair (ER) in 108 patients (100 men, 8 women; mean age, 70 years). The decision to perform ERwas based on comorbidities that precluded open repair (n = 48) and patient choice (n = 60). Graft configuration in the open repair group was tubular (n = 180) and bifurcated (n = 15), and in the ER group tubular (n = 48), aortoiliac/femoral (n = 25), and bifurcated (n = 35). All procedures were performed in the operating department, and radiographic guidance was used in the ER group. Follow-up was by interview, examination, and telephone. In addition, contrast-enhanced computed tomography was performed within the first 10 days after operation, 6 months and 12 months after operation, and then annually thereafter in the ER group. Outcome measures were successful exclusion of the aneurysm sac from the general circulation and survival. Data were analyzed by the life table method. Other outcome measures were length of hospital stay, length of intensive care unit stay, and operative blood loss. RESULTS: No significant difference was found between the perioperative mortality rate for OR (11 deaths [5.6%] in 195 patients) and ER (six deaths [5.6%] in 108 patients). Three of the six deaths in the latter group occurred in patients with successful ER, and three occurred in 18 patients with failed ER who were converted to OR. Similarly, no significant difference was seen in the survival rate between the endoluminal and open repair groups when analyzed by the log-rank test (p = 0.14). The rate of graft failure, however, was significantly higher in the ER group than in the OR group (Fisher's exact test, p < 0.001). Success in the ER group was defined as continuing graft function without endoleak or conversion to open repair. Kaplan-Meier curve for graft failure times for the endoluminal group revealed a 3-year graft success probability of 70%. CONCLUSIONS: This study suggests that ER is safe, sharing the same perioperative mortality risk as OR despite 44% of the ER group being rejected as unfit for OR. Conventional open repair is the most reliable method of successfully managing AAA. The endoluminal method, however, results in shorter length of hospital stay, shorter length of intensive care unit stay, and less blood loss than the open method. Patients who opt for the endoluminal method of repair should be made aware that the minimally invasive technique carries the disadvantage of a higher failure rate.

Aged↗
PubMed1993

Dynamic life table model for Aedes aegypti (diptera: Culicidae): simulation results and validation.

The container-inhabiting mosquito simulation model (CIMSiM) is a weather-driven, dynamic life table simulation model of Aedes aegypti (L.) and similar nondiapausing Aedes mosquitoes that inhabit artificial and natural containers. This paper presents a validation of CIMSiM simulating Ae. aegypti using several independent series of data that were not used in model development. Validation data sets include laboratory work designed to elucidate the role of diet on fecundity and rates of larval development and survival. Comparisons are made with four field studies conducted in Bangkok, Thailand, on seasonal changes in population dynamics and with a field study in New Orleans, LA, on larval habitat. Finally, predicted ovipositional activity of Ae. aegypti in seven cities in the southeastern United States for the period 1981-1985 is compared with a data set developed by the U.S. Public Health Service. On the basis of these comparisons, we believe that, for stated design goals, CIMSiM adequately simulates the population dynamics of Ae. aegypti in response to specific information on weather and immature habitat. We anticipate that it will be useful in simulation studies concerning the development and optimization of control strategies and that, with further field validation, can provide entomological inputs for a dengue virus transmission model.

Aedes↗