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Click on the column headings for an explanation of what they mean. Click on the region names to see the reference from which the data was taken.
| Country | Region | Study date | Population type | Prevalence, per 100,000 | Incidence, per 100,000 | Annual growth rate of Incidence (%) | Peak incidence | Peak age group (Years) | Female:Male ratio |
| Australia | Melbourne | na | na | na | na | na | na | na | na |
| Belgium | Brussels | 30-Mar-93 | Belgian | na | 4.1 | na | na | 20 to 29 | 2.50 |
| Belgium | Brussels | 30-Mar-93 | Moroccan | na | 6.4 | na | na | 20 to 29 | 2.50 |
| Belgium | Liege | 31-May-94 | General | na | 5.5 | na | 13.6 | 20 to 29 | 1.70 |
| Canada | N Alberta | 31-Dec-81 | General | 44.0 | 10.0 | na | na | na | na |
| Canada | S Alberta | na | Female | 63.7 | 6.5 | na | na | na | na |
| Canada | S Alberta | na | Male | 38.1 | 3.1 | na | na | na | na |
| Canada | SE Ontario | na | General | 33.1 | na | na | na | na | na |
| Denmark | Copenhagen | 1987 | General | 54.0 | 4.1 | 7.8 | 12.8 | 15 to 24 | na |
| Denmark | Faroe islands | 31-Dec-83 | General | 31.8 | 1.8 | "insignificant" | na | na | na |
| England | Leicestershire | 1993 | European | 75.8 | na | na | na | na | na |
| England | Leicestershire | 1993 | South Asian | 33.2 | na | na | na | na | na |
| England | North Tees | na | na | na | na | na | na | na | na |
| England | Derby city | 1985 | Caucasian | na | 7.0 | na | na | na | na |
| England | Derby city | 1985 | West Indian | na | 4.5 to 5.6 | na | na | na | na |
| France | Paris | na | na | na | na | na | na | na | na |
| Germany | Cologne | 30-Jun-86 | General | 30.7 | 5.1 | na | 17.3 | 20 to 24 | 1.57 |
| Greece | Crete | 1994 | General | na | 3.8 | 14.9 | 6.3 | 25 to 34 | 0.42 |
| Holland | Regio Leiden | 1983 | General | 48.0 | 3.9 | na | na | 20 to 29 | na |
| Hong Kong | Hong Kong | na | na | na | na | na | na | na | na |
| Israel | Kinneret | 1990 | Jewish | 45.9 | 3.0 | 1.4 | na | na | na |
| Israel | South | 31-Dec-92 | Jewish | 50.6 | 4.2 | na | na | na | na |
| Israel | South | 31-Dec-92 | Bedouin | 8.2 | na | na | na | na | na |
| Italy | Bologna | 1993 | General | na | 7.7 | na | na | 20 to 29 | na |
| Japan | Nationwide | 1991 | General | 5.9 | 0.5 | na | na | na | na |
| Kuwait | Kuwait | na | na | na | na | na | na | na | na |
| Norway | Southeast | 31-Dec-93 | General | na | 5.8 | na | 11.2 | 15 to 24 | na |
| Norway | Western | 1985 | Children | na | 2.5 | na | na | na | na |
| Portugal | Oporto | na | na | na | na | na | na | na | na |
| Scotland | Aberdeen | 1987 | General | na | 11.6 | na | na | na | 1.70 |
| Scotland | Northeast | 31-Dec-88 | General | 147.0 | na | na | na | na | 1.70 |
| Scotland | Orkney | 1988 | General | na | 6.1 | na | na | na | na |
| Scotland | Shetland | 1988 | General | na | 5.7 | na | na | na | na |
| Singapore | Singapore | na | na | na | na | na | na | na | na |
| Slovakia | Nationwide | 30-Apr-94 | General | na | 6.8 | na | na | 30 to 49 | na |
| Spain | Granada | 1988 | General | na | 0.9 | na | na | na | na |
| Spain | Aragon | 1992 | General | na | 3.3 | 6.9 | na | na | na |
| Spain | Central | 1988 | Urban/Rural | 19.8 | 1.6 | "Significant" | na | na | na |
| Sweden | Southwest | 1987 | Children | 21.5 | 5.3 | na | na | na | na |
| Sweden | na | 1-Mar-90 | Adult | 94.0 | na | na | na | na | na |
| Sweden | Uppsala | 1983 | General | na | 7.0 | na | na | na | na |
| Sweden | Malmo | 31-Dec-73 | General | 75.2 | 6.0 | 2.2 | na | na | na |
| USA | Minnesota | 1975 | General | 105.7 | 6.6 | 3.1 | na | na | 1.00 |
| USA | Rochester NY | 1986 | General | na | 5.0 | na | na | 20 to 29 | na |
| USA | Spokane WA | 1981 | General | na | 8.8 | 3.7 | na | na | na |
| Wales | South Glamorgan | 1993 | Children | 16.6 | 3.1 | 9.1 | na | na | na |
| Wales | Cardiff | 1977 | General | na | 4.8 | 10.1 | na | na | na |
| Wales | Cardiff | 1985 | General | na | 8.3 | 6.3 | na | na | na |
| Wales | Cardiff | 1990 | General | na | 5.9 | -6.6 | na | na | na |
| Yugoslavia | Nationwide | 1992 | General | 3.2 | na | na | na | na | na |
This describes the subset of the general population that has been studied. Some studies only study the general population, and the population type for these is "General". Others study only children. The population type for these is "Children". Others study ethnic groups, and in these the population is, for example, "Caucasian", "Bedouin", "Asian", etc.
The prevalence of a disease describes the number of people in the population studied who have the disease. The figure is always quoted in sufferers per hundred thousand. For example, if the prevalence figure is 50 per 100,000, and the population of the study is one million, then 500 people have the disease in that population. The prevalence of a disease is always changing, since new people develop the disease, and people with the disease pass away. Point prevalence is the prevalence on a given date, e.g. 31 December 1996. Period prevalence is averaged over a period of time, perhaps a year, e.g. 1995.
The incidence of a disease describes how many people in a population develop the disease per year. The figure is always quoted in new cases per hundred thousand. For example, if the prevalence figure is 10 per 100,000 per year, and the population of the study is one million, then 100 people will develop the disease in that year in that population. Sometimes, incidence is quoted per decade, so to get the yearly incidence, you must divide by ten, since there are ten years in a decade.
The incidence of a disease changes from year to year. In some years, the incidence may fall, or it may rise. Some of the studies quoted on the statistical table describe the change in incidence from the start of the study to the end. In these cases, I have worked out what the percentage of change in incidence is, on a yearly basis. For example, take a three year study. If the incidence is 100 per 100,000 in the first year, and the annual growth rate of incidence is 10%, then in the second year, The incidence will be 110 per 100,000 and in the third year the incidence will be 121 per 100,000. This gives a total of 331 people who develop the disease in the three year period.
Some of the studies show averages of incidence of a range of years, one period at the beginning of the study and the other at the end of the study. In these cases, I assume that the rate of the start period begins at the start of the period, and the rate of the end period ends at the end of the last period. This has the effect of underestimating the rate of growth, but I think it is better to underestimate than overestimate.
Diseases affect people differently, depending on age, sex, etc. Many studies tell the age group that is most affected by the disease, and what the incidence of the disease is in that age group. This is the "Peak Incidence".
The "Peak age group" is the age group for which "Peak Incidence" is quoted, i.e. it is the age group most affected by the disease.
In most parts of the world, Crohn's disease affects women more than it does men. In the table is given the ratio of female sufferers to male. If the ratio is 2.0, then for every hundred men that have the disease, two hundred women have it. If the ratio is 0.4, then for every hundred men that have the disease, forty women have it.
Source: http://archive.crohn.ie/epistats.htm
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