Aim: Estimate the burden of morbidity from routinely available data. This burden of morbidity is measured as the dependence to health services.
Numerator: Each calendar day of people (healthy or not) receives an ill weight, ranging from zero (healthy) to 1.00 (severe illness). A coefficient of 1.00 correspond to inpatients’ stays in hospital or nursing home, to home care by nurse, or to a physician or a physiotherapist’s visit (Table 1). If a patient received several types of services on the same day, the illness day is allocated to the first service from the above list with a maximal value of 1.00. Ill patients might be ill between two physician or physiotherapist’s visits, especially if visits are close from each other. Thus, a decreased function of time was applied to compute ill weights, depending on the delay between two visits (Table 1). For instance, if a patient received two visits in an interval of 4 days, he was considered as ill during these 4 days. If the delay was greater than 4 days, the weight was reduced to 0.323 for a delay of 9 days, 0.106 if the delay was 20 days and to 0 after 24 days. If patients did not receive any of the above services but drugs, illness coefficients were set from 0.05 (preventive treatment) to 1.00 (severe illnesses), with duration depending on the nature of the illnesses (Table 2).
|Table 1. Ill weights|
|Hospitalization||1.00||during the stay and twice the length|
|of stay after|
|Nursing home||1.00||during the stay|
|Home care by nurse||1.00||every day with a visit|
|Physician and physiotherapist||1.00||every day with a visit, and w for each day between two visits, with w = 7/d1.04 , where d is the delay (in days) between the two visits. If d > 24, w = 0.|
|Delivery of drugs:|
|- symptoms||1.00||3 days after drug delivery|
|- acute diseases||1.00||7 days after drug delivery|
|- subacute diseases||0.50||60 days after drug delivery|
|- preventive treatment||0.05||365 days after drug delivery|
|- dementia||1.00||365 days after drug delivery|
|- polyarthritis and other inflam.||0.25||365 days after drug delivery|
|- other chronic diseases||0.50||365 days after drug delivery|
|Table 2. Type of illnesses (inferred from drugs)|
|Symptoms:||goddiness and deafness, migraine, pain.|
|Acute diseases:||cardiac dysrhythmia, eye infection, gastroenteritis or gastrointestinal ulcer, gastrointestinal specified infection, gout and secondary arthropathies, hepatitis, infection not classified elsewhere, inflammatory dermatitis, influenza or acute bronchitis, localised skin infection, ther acute ischemic heart disease, other endocrine disease, other infection of female organ, other psychiatric disorder, other pulmonary infection, other upper respiratory infection, thyroid disorders|
|Sub-acute diseases:||agranulocytosis, alcohol abuse, chemotherapy, chronic bronchitis and asthma, deficiency anemia, depression, inflammatory entero-colitis, multiple sclerosis, other anemia, other substance abuse, psychosis, hallucination and delirium.|
|Preventive treatment:||acquired immunodeficency syndrome, degenerative disease of bones, diabetes, epilepsy, glaucoma, non-severe hypertension, obesity, other coagulation disorder, prostatic hyperplasia, transplant recipient.|
|Chronic diseases:||dementia, polyarthritis and other inflammation, chronic nephropathy, heart failure, Parkinson’s diseases.|
Denominator: Number of calendar days in the whole studied population.
Output files: Results are given by insured in “Ill_weights.txt” file, with following variables:
#Insured Identifier of insured
Gender 1 = male, 2 = female
Days Sum of ill weights during the year
Interpretation: The morbidity burden corresponds to the number of days during which people depend on the health system.
Strength of the indicator: This method takes into account the actual duration of the illness, based on objective data, which is not the case when the morbidity is estimated through subjective questionnaires. Another advantage is that routinely available data (insurance bills) are sufficient to produce the indicator. This enables the estimation of the morbidity burden for the whole population without costly inquiries.
Limitations: A first limitation is related to illnesses generating suffering to patient, which might not consume health services because the latter are not very effective. For instance, people suffering from stroke or multiple sclerosis might have only limited contact with the health system. A second limitation might results from comparability issues. Indeed, countries with few health facilities might have a low morbidity burden just because of a lack of access to health resources. Therefore, we recommend the indicator to be used in regions with a similar access to health services.