Effect Of Case Mix Research Articles

The effect of casemix adjustment on mortality as predicted by APACHE II.

To describe the effect of casemix on mortality as predicted by APACHE II scoring. Retrospective analysis of an ICU database. All patients admitted to 19 ICU between 1 January 1992 and 31 May 1994 on whom data had been entered into a database. Excluded from the analysis were those readmitted to ICU, those aged under 16 years, those admitted after cardiac surgery or with burns, those for whom physiological data was incomplete and those for whom hospital outcome was unknown. Data on the remaining 6258 patients are reported. APACHE II scores were calculated from the worst values within 24 h of ICU admission. Hospital mortality was predicted with the published equation and coefficients. Mortality ratios (observed hospital deaths divided by predicted hospital deaths) were calculated for various groups. Mortality ratios varied widely by subgroup, and observed hospital deaths were greater than predicted, particularly for the following patient groups: those with predicted mortality of less than 70%, those with APACHE II scores in the range of 5-19, those older than 55 years, those with a Glasgow Coma Score of 15 or in the range 9-14, those not having emergency surgery, those with either 0 or 4 chronic health points and those in non-operative respiratory or neurological categories. The mortality ratio was markedly less than 1.0 only among non-operative cardiovascular patients. APACHE II did not accurately adjust for casemix in our data. Unless account is taken of differences in casemix, using mortality ratios to compare ICU is likely to be inaccurate and misleading.

Measuring the effects of casemix on outcomes

Participation in the measurement of population health and health care outcomes has become an explicit professional duty for doctors, but comparisons are difficult to make because outcomes are conceptually complex and largely qualitative. Observational data, particularly from routine hospital statistics, are useful complements to experimental data provided that their variable quality is taken into account and adjustments are made to minimize bias and confounding and to allow for the effects of differences in casemix, which are problematic because of the nature of severity.

Evaluating perinatal mortality rates: effects of referral and case mix.

To evaluate perinatal mortality rates as a method of auditing obstetric and neonatal care after account had been taken of transfer between hospitals during pregnancy and case mix. Case-control study of perinatal deaths. Leicestershire health district. 1179 singleton perinatal deaths and their selected live born controls among 114,362 singleton births to women whose place of residence was Leicestershire during 1978-87. Crude perinatal mortality rates and rates adjusted for case mix. An estimated 11,701 of the 28,750 women booked for delivery in general practitioner maternity units were transferred to consultant units during their pregnancy. These 11,701 women had a high perinatal mortality rate (16.8/1000 deliveries). Perinatal mortality rates by place of booking showed little difference between general practitioner units (8.8/1000) and consultant units (9.3-11.7/1000). Perinatal mortality rates by place of delivery, however, showed substantial differences between general practitioner units (3.3/1000) and consultant units (9.4-12.6/1000) because of the selective referral of high risk women from general practitioner units to consultant units. Adjustment for risk factors made little difference to the rates except when the subset of deaths due to immaturity was adjusted for birth weight. Perinatal mortality rates should be adjusted for case mix and referral patterns to get a meaningful result. Even when this is done it is difficult to compare the effectiveness of hospital units with perinatal mortality rates because of the increasingly small subset of perinatal deaths that are amenable to medical intervention.

Mixing effects, optimisation, and dispersion modelling in bleachable and sensitised photoreaction mixtures

Radiation attenuation leads to mixing effects in photoreactors. Several characteristics of these mixing effects as found in bleachable chain reaction m Chain center mixing always enhances reactor performance while reactant mixing sometimes diminishes it. In either case mixing effects in bleachable syst An axial dispersion model was used to represent the combined effects of diffusion, non-uniform reaction rate distribution, and non-uniform velocity dis showed that at small optical thicknesses the axial dispersion coefficient approached that for a completely homogeneous reactor while at large optical t