Confirmatory Factor Analysis Using PROC CALIS: A Practical Guide for Survey Researchers

ABSTRACT Survey research can provide a straightforward and effective means of collecting input on a range of topics. Survey researchers often like to group similar survey items into construct domains in order to make generalizations about a particular area of interest. Confirmatory Factor Analysis is used to test whether this pre-existing theoretical model underlies a particular set of responses to survey questions. Based on Structural Equation Modeling (SEM), Confirmatory Factor Analysis provides the survey researcher with a means to evaluate how well the actual survey response data fits within the a priori model specified by subject matter experts. PROC CALIS now provides survey researchers the ability to perform Confirmatory Factor Analysis using SAS ® . This paper provides a survey researcher with the steps needed to complete Confirmatory Factor Analysis using SAS. We discuss and demonstrate the options available to survey researchers in the handling of missing and "not applicable" survey responses using an ARRAY statement within a DATA step and imputation of item non-response. A simple demonstration of PROC CALIS is then provided with interpretation of key portions of the SAS output. Using recommendations provided by SAS from the PROC CALIS output, the analysis is then modified to provide a better fit of survey items into survey domains

Completely resected N1 non–small cell lung cancer: Factors affecting recurrence and long-term survival

ObjectiveN1 disease in non–small cell lung cancer represents a heterogeneous patient subgroup with a 5-year survival of approximately 40%. Few reports have evaluated the correlation between N1 disease and tumor recurrence or which subgroup of patients would most benefit from adjuvant chemotherapy.MethodsFrom 1997 through 2002, all patients with pathologic T1-4 N1 M0 non–small cell lung cancer who had a complete resection with systematic mediastinal lymphadenectomy were retrospectively analyzed and evaluated for factors associated with recurrence and long-term survival.ResultsOne hundred eighty patients with N1 disease were evaluated. Sixty-six (37%) patients had either locoregional recurrence (n = 39 [22%]), distant metastasis (n = 41 [23%]), or both during follow-up. Univariate analysis demonstrated that visceral pleural invasion and age were associated with locoregional recurrence, whereas visceral pleural invasion, distinct N1 metastasis (as opposed to direct N1 invasion by the primary tumor), and multistation lymph node involvement were associated with distant metastasis (P < .05). Multivariable analysis demonstrated that visceral pleural invasion, multistation N1 involvement, and distinct N1 metastasis were the only independent predisposing factors for locoregional recurrence and distant metastasis. Overall 5-year survival was 42.5%. Survival was significantly decreased by advanced pathologic T classification (P = .015), visceral pleural invasion (P < .0001), and higher tumor grade (P = .014).ConclusionsIn patients with N1-positive non–small cell lung cancer, visceral pleural invasion, multistation N1 disease, and distinct N1 metastasis are independent predictors of subsequent locoregional recurrence and distant metastasis. Advanced T classification, visceral pleural invasion, and higher tumor grade were predictors of poor survival. These patients represent a subgroup of patients with N1 disease who might benefit from additional therapy, including adjuvant chemotherapy

Safety, Feasibility, and Short-term Outcomes of Laparoscopic Ileal-Pouch-Anal Anastomosis: A Single Institutional Case-Matched Experience

OBJECTIVE: To compare safety and short-term outcomes of 100 laparoscopic ileal pouch-anal anastomosis (IPAA) versus 200 conventional open IPAA patients. SUMMARY BACKGROUND DATA: Outcomes of laparoscopic IPAA (LAP-IPAA) have been incompletely characterized. Previous reports are characterized by small numbers of patients and rarely include case-matched or randomized trial methodology. This report describes 100 LAP-IPAA patients case matched to 200 open IPAA patients. METHODS: Between 1998 and 2004, 100 consecutive LAP-IPAA patients (75 laparoscopic assisted, 25 hand assisted) were identified and case matched to 200 open IPAA control patients by age, operation, gender, date of operation, and body mass index. Operative and postoperative outcomes at 90 days were compared. RESULTS: A total of 300 patients (180 female) with a median age of 32 years (range, 17–66 years), and a median body mass index of 23 kg/m(2) (range, 16–34 kg/m(2)) underwent IPAA (100 LAP-IPAA, 200 open IPAA). Diagnosis (chronic ulcerative colitis 97%, familial adenomatous polyposis 3%) and previous operative history were equivalent between groups. One intraoperative complication occurred in each group. Overall, the laparoscopic conversion rate was 6%. Median operative time was longer for the LAP-IPAA group (333 minutes versus 230 minutes, P < 0.0001). LAP-IPAA patients had shorter median time to regular diet (3 versus 5 days), time to ileostomy output (2 versus 3 days), length of stay (4 versus 7 days), and decreased IV narcotic use (all P < 0.05.Postoperative morbidity was equivalent (LAP-IPAA = 33%, open IPAA = 37%), mortality was nil, and readmission rates were equal (LAP-IPAA = 21%, open IPAA = 22%). Reoperation was required in 3% of LAP-IPAA and 6.5% of open IPAA patients (P < 0.2) during the first 3 months. CONCLUSION: LAP-IPAA is equivalent to open IPAA in terms of safety and feasibility. In addition, LAP-IPAA provides significant improvements in short-term recovery outcomes