Accessibility and connectivity in physical activity studies: the impact of missing pedestrian data.

OBJECTIVE: One important characteristic in physical activity research into the built environment is network connectivity, usually calculated using street networks. However, a true pedestrian network may have very different connectivity than a street network. This study, conducted in 2004, examines the difference in walkability analyses when street networks versus pedestrian networks are used for four metropolitan suburbs in Perth, Western Australia. METHODS: A street network of Perth was used to represent the current standard of data for walkability analyses. Aerial photography from 2003 was used to create a pedestrian network, which incorporated pedestrian footpaths into the street network. The street and pedestrian networks were compared using three measures of connectivity: Pedsheds, link node ratio and pedestrian route directness. RESULTS: A comparison of the results using street versus pedestrian networks showed very different outcomes for conventional neighbourhood designs. Connectivity measures for conventional neighbourhoods improved up to 120% with the addition of pedestrian networks, although traditional neighbourhoods still had slightly better connectivity values overall. CONCLUSION: The true pedestrian network increases the connectivity of a neighbourhood and may have significant impact on these measures, especially in neighbourhoods with conventional street designs. It is critical that future studies incorporate pedestrian networks into their analyses.

Impact of laparoscopic cholecystectomy on hospital utilization.

OBJECTIVE: The objective of the present study was to assess the impact of laparoscopic cholecystectomy (LC) and associated endoscopic retrograde pancreatography (ERCP) on hospital utilization. BACKGROUND: Laparoscopic cholecystectomy (LC) has resulted in marked reductions in average length of hospital stay; but population-based studies of hospital utilization have generally not taken into account increased cholecystectomy rates or associated increases in pre and postoperative admissions. METHODS: We conducted a population-based study of all residents of Western Australia who underwent cholecystectomy in the period 1980-2000. Record linkage was used to identify pre and postoperative admissions, and to estimate aggregate length of stay per case based on all relevant admissions. We estimated trends in cholecystectomy rates, proportions of cases with related pre and postoperative hospital admissions, average aggregate length of stay per case and total bed utilization per unit of population. RESULTS: The introduction of LC was associated with a sustained increase in rates of cholecystectomy of 25%. Similar increases occurred in the percentage of cases with related preoperative and postoperative admissions. Average length of stay for index admissions declined by nearly 60% compared with 50% for all related admissions. Per capita hospital utilization for index admissions decreased by 45% compared with 38% for index and associated admissions combined, and 32% for all admissions for biliary disease. CONCLUSIONS: Reduced hospital utilization associated with LC was partly offset by increases in pre and postoperative admissions and a sustained increase in cholecystectomy rates. Record linkage is required to assess the true impact of new technologies on hospital utilization.