Daily, monthly and yearly fluctuations in total number of suicides and suicide attempts in the western part of the Netherlands
Titel:
Daily, monthly and yearly fluctuations in total number of suicides and suicide attempts in the western part of the Netherlands
Auteur:
Bouma, Janneke J. Tromp, S. W.
Verschenen in:
Biological rhythm research
Paginering:
Jaargang 3 (1972) nr. 3-4 pagina's 269-270
Jaar:
1972-12
Inhoud:
In most published reports, discussing suicide problems, only mortality resulting from suicide attempts has been used as a basis for all statistical analyses. The main reason for this procedure is the great difficulty in obtaining accurate morbidity data with reference to suicide attempts. However, as the total number of suicides in a city or country represents 1/6 to 1/10 of the real number of suicide attempts, it is evident that all published conclusions must be accepted with the greatest possible reserve. Both authors were able to collect rather trustworthy data at the Municipal Medical Health Services (GG and GD) of the cities of The Hague, Amsterdam and Rotterdam and at the University Medical Centre at Leiden and Utrecht. Particularly the psychiatric departments of the GG and GD services in these three mentioned cities have an excellent record of most suicide attempts in these cities and a follow up system which enabled them to collect for each case, apart from name, sex, date of birth, marital status and religion, also date and hour of suicide, respectively suicide attempt, consequences of the attempts, method applied for the attempts (drugs, gas etc.), the possible reason for the attempt, number and dates of previous attempts, psychiatric diagnosis. These detailed records started in The Hague in 1954, in Rotterdam in 1959, in Amsterdam in 1961, in Utrecht and Leiden in 1965. Alltogether about 10,000 well described cases were collected by the authors and analysed for various purposes. Some of the major results of their analyses were the following: The average daily number of reported suicide attempts is usually less than one case a day, often even one case per 2 or 3 days. On certain days there is a sudden increase of 300 - 750%, i.e. 2 to 5 cases per day. Alltogether 789 of such cluster days were observed. These DAILY FLUCTUATIONS in frequency of suicide attempts have no direct relationship with simple meteorological parameters such as environmental temperature, windspeed, hours of sunshine etc. However, there is a statistically significant relationship between cluster days and periods with strong atmospheric turbulence, accompanied by drastic changes in thermal balance (either cold or warm) and heavy precipitation (rain, snow or hail), causing serious thermoregulatory disturbances. They seem to trigger in subjects, predisposed to a serious mental disturbance, a suicide attempt. It is remarkable that no clusters occurred on the major holidays in The Netherlands, such as Saint Nicolas (5 December), Christmas and New Year. No consistent SEASONAL FLUCTUATIONS were observed in the period 1954 to 1970. In The Netherlands as a whole and in Rotterdam in particular, the lowest suicide incidence occurs in January. In the case of suicide attempts January and February have usually the lowest values. The maximum number of suicide cases occurs in different years, in different months; however, suicide attempts are usually most frequent in the period September-November, the months with usually the greatest drastic meteorological disturbances. There is some evidence for YEARLY FLUCTUATIONS: SUICIDES in The Netherlands as a whole increased from 1955 till 1959, decreased till 1963, followed by a new increase till 1966 and a new decrease after 1966. SUICIDE ATTEMPTS in The Hague and Rotterdam show a similar pattern. The yearly number increases from 1955 (perhaps even earlier) till 1960 (The Hague) and 1961 (Rotterdam) followed by a decrease in 1962 and 1963. Since 1963 a new rise till the end of 1967 (in Rotterdam) and 1969 (in The Hague), followed in Rotterdam by a decrease in 1968 and 1969 and a new rise in 1970. No simple sociological explanation could be found for these long term fluctuations. It is worth mentioning that the DISTRIBUTION OF THE MONTHS OF BIRTH of subjects committing suicide attempts is entirely different from the pattern of the normal healthy population. The 10,000 subjects, who committed suicide in the period 1954 to 1970, were born most frequent in February and March, whereas in the normal population it is the month of May.
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