Aim: Compare observed and expected values of ambulatory costs per patient, taking into account possible random fluctuations.
Definition: Observed cost per patient is equal to the sum of the amount of ambulatory costs.
Ambulatory costs include all health costs covered by LAMal, except if the nature of the bills are hospitalizations, semi-hospitalizations, nursing home, and maternity, which are all beyond the influence of reference physicians (generalists and internists). Semi-hospitalizations correspond to :
– bills with « day hospitalisation » as nature
– bills greater than 1000 CHF if the specialty of the provider is cardiology, ENT, gastroenterology, gynecology & obstetrics, hematology/oncology, ophtalmology, orthopedics, surgery, transport, urology, day hospitalisation (specific list updated every year).
Expected cost per patient correspond to average costs per risk stratum (ambulatory grouper) observed in 2017, after removing outliers (costs greater than 6 times or lower than 1/6 of average cost).
Minimal and maximal expected costs are given, according to the methodology below:
Rousson V, Le Pogam MA, Eggli Y. Control limits to identify outlying hospitals based on risk-stratification. Statistical Methods in Medical Research, 2016 (0 :1-14) for more details).
Interpretation: If the observed costs exceed expected ones (ratio of cost > 1.0), this means than the costs of the patients allocated to a specific reference physician might be too high in general.
If the observed cost per physician exceed the maximal expected cost, this mean that the over-cost is statistically significant.
The difference between observed and expected rates give the average over-cost or economy per patient. Multiplying this amount by the number of patients, this gives the financial impact for each reference physician, considered as gatekeeper.
Validity of the results: Several factors might influence the validity of results, for instance:
- unknown diseases (cannot be inferred from drugs’ consumption)
- severity issues (patients more ill in each specific risk strata)
- patient consulting other doctors without control from the reference physician