Analysis of the Underlying and Multiple Causes of Death for the Kuwaiti Population 40 years or over ; Part II : Causes

Background: Death rarely results from a single cause; it can be caused by a variety of factors. Multiple causes of death (MCD) can provide information about the associations between causes of death revealing common combinations of conditions. Moreover, they can rectify inconsistencies in the death certificates (DC). Objective: This paper is meant to highlight the importance of multiple causes of death and point out the contributing and associated disease conditions to the underlying cause of death (UCD). Methods: The study was based on analysis of multiple causes of death for the Kuwaiti population 40 years or over in the period 1993-2001. All multiple causes up to 5 in the death certificate notification (DCN) were coded and analyzed. The data were coded according to ICD9 following the WHO rules. The ratios for the MCD/UCD were computed for the groups of diseases and for individual causes exceeding 50 entries. The relative ratios (Observed/Expected) were computed to show the associations between the groups of causes. Results: A total of 13960 DCNs were analyzed, the ratios were low for neoplasms (1.51), followed by respiratory (2.50), nervous (2.97), and digestive conditions (3.01), Ill-defined conditions had the highest ratio (13.40). Infections and genitourinary diseases had ratios of 4.19 and 4.56. Ranking changed when using MCD; circulatory, endocrinal, nervous and digestive conditions kept their position, with circulatory diseases on the top and nervous conditions occupying position 10. Relative risk (RR) was computed for the different groups; positive RR was found between infections and respiratory, digestive, genitourinary and ill-defined disease conditions. Neoplasms showed positive association was other neoplasms, and endocrine conditions were positively associated with circulatory, respiratory, and genitourinary conditions. A positive association was found between illdefined conditions with circulatory and other Ill-defined conditions. Conclusions: UCD is still essential to analyze historical trends, compare countries, and guide prevention of death; MCD offer a new sight into the study of mortality. The combination of the 2 methodologies is more useful than the isolated use of either approach. Conclusion and Recommendations: The Collection of MCD is essential, there has been major development in the area and soft ware was developed to analyze MCD data. MOH should start the development of data bases for MCD, make them available, and include the highlights in the MOH annual reports. Special reports discussing individual disease conditions particularly neoplasms and circulatory and respiratory conditions should be organized.


INTRODUCTION:
Mortality statistics are used in epidemiology and public health as an indicator of health status, to evaluate health programs, and in population studies to compare trends and spatial differences. (1)Mortality statistics can be compiled using the underlying cause (UCD) or multiple causes (MCD).Deaths rarely have only one cause and using the UCD will not allow researchers to assess the role of conditions that are important contributors to death but were not reported as the UCD. (2)Analyses that use only the UCD ignore a lot of information that is readily available and underestimate the importance of several leading causes of death. (3)Wall et al. (4) stressed the analytical potential of MCD and pointed its use of looking for inaccuracy in reporting the cause of death.The last century was characterized by a persistent increase in survival, resulting from improved quality of nutrition and living conditions, and progress in medical technology and health care. (5)e pattern is however complicated, the mortality rates from CVD substantially declined during the second half of the last century; mortality from cancer however increased until that time and slightly decreased thereafter. (6)e selection of a single UCD is frequently problematic in the elderly people who often have several chronic diseases that concurrently lead to death. (7)storically reliable, representative routine low cost and long term mortality measurements have been the key to monitoring trends in health conditions of the population, detecting new epidemics , spurring research into avoidable causes of death, evaluating the success of control programs and improving accountability of expenditure on disease control. (8)Routinely collected data have helped to spur further research and public health action and contributed to the enormous increase in life expectancy in the last century. (9)he relative frequency with which a cause is selected as the underlying cause of death will influence the position of this disease in order of importance in the official statistics of mortality in any country.
However, knowing how many times any disease is registered on the death certificate would serve health services as an indirect indicator of their prevalence and impact on the population. (10)The causal pathway generally reflects the attending physician's best judgment about the causal train of events and will be influenced by his reasoning; the association between causes of death can be pointed by examining the frequency with which the conditions are reported together. (3)he biological plausibility of a connection between 2 conditions; and the opinion of the person filling the death certificate is critical. (3)ile examining the absolute numbers and ratios of MCD provide valuable information about the relative magnitude of the different disease conditions, there are other important analytical uses; MCD can be used to examine the links between the different causes listed on the death certificate (DC), ultimately this potential is of great value to health authorities. (2)A simple way to investigate the association between the causes of death is to compute the percentage of deaths involving a particular disease condition which also involves another specified cause, (11,3) The biological plausibility of a connection between the 2 conditions may determine the decision of the physician in charge.
The strength of the association can be measured by comparing the ratio in which the 2 causes are mentioned together and the number of cases that might be expected under the assumption of the 2 conditions being independent; (3) the method was adopted and applied by the Australians. (11)An observed ratio higher than 1 indicates that the 2 conditions may have a positive association. (12)e Ministry of Health in Kuwait (MOH) Bull High Inst Public Health Vol.39 No. 3 [2009]   publishes the age, sex and nationality distribution of the first hundred causes in the annual reports; (13)  Department is in charge of verifying the DCNs and their UCD coding.
The causation matrix was done by cross tabulation of the disease conditions, the relative ratios (RR) were computed along the method applied and elaborated by the Australians (ABS 2003), (11) originally reported by Stallard. (12)The RR is

RESULTS:
The relative distribution of the multiple causes of death at the chapter level for the males is shown in were the third on the list of the UCD (8.8%), followed by the respiratory (6.0%) and ill-defined conditions (6.2%).Similar to the males, ill-defined conditions were quite common as a third cause (61.3%).
Infections were contributing a total of 3.7% of the MCDs, the relative contribution was slightly higher with the cause number 4 (8.1%).Injury contributed slightly less than that for the males, accounting for 2.1% of the total and was 2.3 % of the UCD.
Respiratory, digestive and genitourinary diseases accounted collectively for 10.1% of the total entries.The rising trend seen with the endocrinal diseases was more obvious in case of females.
The change in the mortality pattern using the multiple cause of death in place of the underlying cause at the chapter level for the males and females is summarized in Endocrinal and metabolic conditions ranked third in the 2 causation categories.
Nervous system diseases were at the bottom of the list using the UCD or the total causes.Infections were the 9 th on the UCD and moved to the 8 th position on the MCD list; genitourinary conditions were the 7 th and kept that rank with the 2 lists.The group of ill-defined conditions, which occupied the 6 th position moved to occupy the 2 nd on the MCD.With females the order of neoplasms, and circulatory, endocrine, nervous and digestive system diseases were the same as that for the males.Infections which moved up with the males moved down with the females, from the 7 th to the 8 th position.
The association of the different causes using the MCD is summarized in

DISCUSSION:
This is the 2nd of a series of papers To highlight the differences the findings (table 1) were compared with the MOH figures for 1998, (13) the mid year for the present study (1993-2001) were appreciably higher with the MOH.It should be noted that the comparison is done for the UDC and not the MCD.The differences are mostly attributed to the difference in age.
The disease conditions analyzed in the present study are all those mentioned in the DCN; it should be noted that these would include both the contributing and associated disease conditions, a point that was discussed by Deshpande, (14) who presented the 2 conditions individually.Bah (15) presented results for South Africa as the UCD, the number of contributing disease conditions, beside the total.In the present study, the disease conditions that showed-up by using the MCD analysis included illdefined conditions (11.4 times the Within the limitations mentioned for this study; data from Australia for 2004 (16) were comparable to Kuwait, the ratio for infections (5.5) was higher than Kuwait, but the ratio for neoplasms was very close to that for Australia (1.4), the ratio for endocrine and metabolic diseases (3.9) was slightly higher than Kuwait.
The ratios for mental and nervous disease in Australia (5.3 and 4.1) were higher than the corresponding ratios for Kuwait, the ratio for the circulatory diseases in Kuwait was higher than that for Australia as a whole (3.0).It is worth noting that the overall ratio for Kuwait (3.71) was higher than that for Australia (2.9); moreover the data for Australia covered all the age groups which is different from the present study.
The ratio for the ill-defined conditions (13.4 for Kuwait and 16.8 for Australia) were close, also both had the highest ratio compared to any disease group, both were much higher than that for Minnesota in the period 1990-1998 (2.96), however the ratio for Canada (19.98) was higher than that for Kuwait.
It is interesting to note that many workers thought that using the ill-defined ICD9 codes is a sign of poor quality of the data. (7)In Kuwait, the major use of these conditions was as a third cause; the physicians were in no obligation to mention any other cause and they already had two definite valid causes on the DCN and would have been satisfied with However, it seems they were aware of the need to use these codes.
This point needs to be elaborated further.
Ranking of the 10 leading causes of deaths was computed in a manner similar to that reported for the US 2000-2001; (17) several disease conditions kept their position, but some others moved to a higher or a lower position.The order of the disease conditions was somewhat different from that reported for Australia; where neoplasms were on the top of the list.This is expected since they ranked IHD, CVS conditions, and HF separately; Data from Canada (18) showed a pattern different from Kuwait, the illdefined conditions were on the top of the list as an UCD but moved to position 8 with MCD; mental disorders were ranked homicides were reported separately.
The data from Canada included the congenital and prenatal conditions which are not expected for the age structure of the data from Kuwait.
The causation matrix developed for the MCD in this study was designed in line with the one used by Australia (11) where for Brazil. (19)The relation of the ill-defined causes and circulatory system diseases was similar to finding for the Iranian Islamic republic. (20).

CONCLUSIONS:
Analysis

RECOMMENDATIONS:
The collection of MCD is essential, there has been a major development in computed by dividing the actual ratio by the expected, assuming independence of the 2 conditions.Values higher than unity denote association.The expected frequency is computed by multiplying the number of deaths in which cause one is present by the number of deaths in which cause 2 is mentioned and dividing the product by total number of deaths for the time.The RR was computed at the ICD chapter level and not for the individual disease condition to give a holistic approach.The data were tabulated and cleaned using Excel program.Statistical manipulations were done by SPSS for Windows version 14.
that discuss the MCD in the Kuwaiti population 40 years or over.This paper is meant to highlight the medical aspects and point out the contributing and associated disease conditions to the UCD in this group.It is designed to fill a gap in the mortality data published in the MOH annual reports , (13) based on the UCD alone.The findings are not directly comparable to those published by the MOH since the present study was limited to the Kuwaiti population 40 years or over.This age selection will practically exclude almost all congenital anomalies, prenatal and childhood diseases and a major portion of traumatic injuries seen in children and young adults.Selection of those 40 years or over will highlight the chronic and degenerative diseases seen more frequently now in Kuwait, particularly among the nationals. figures).

combining the 3
disease conditions would put the circulatory diseases before neoplasms or any other group.Injuries were also split between injury, poisoning and other consequences and general accidents.The order of diabetes in Australia had position 9 and 6 but it was the 3 rd in Kuwait as UCD, and moved to position 5 with MCD.

4 th and 5
th in Canada, diabetes occupied the 2 nd position as UCD and moved to the top with the MCD data.Suicide and Bull High Inst Public Health Vol.39 No.3 [2009] the individual MCD was cross tabulated with the other MCD cited on the DC.The one for Kuwait is for the total chapter data, and that for Australia was done for selected disease or groups of disease conditions.This is an important dimension to the MCD analysis, providing the capability to point out the possible association between different disease conditions and quantify the magnitude of the associations considering the clinical logic.The causes did not include the UCD, and the computation of RR was done for the different chapters, many of them included many disease conditions.The magnitude of the association can be interpreted by comparing the relative ratios (RR).Neoplasms showed a strong association with the other types of neoplasms, and a lower but still positive RR was seen with respiratory, digestive and genitourinary conditions; this is quite logic, the 3 system organs were among the major neoplasm sites.The high level of association with neoplasms in other sites is expected and secondries often settle in the lungs and liver.Illmajority of these cases were the unattended deaths as reported of causes of death must focus on multiple causes and not aim only at knowing the underlying cause, especially at the country level.The multiple-cause analysis has also brought out the importance of certain diseases as contributing causes of death and deemphasized the importance of illdefined causes of death, genitourinary conditions, infections, endocrine and circulatory conditions.Although underlying causes of death are still essential to analyze historical trends, compare countries, and guide the prevention of death, yet multiple cause of death data offer a new insight into the study of mortality.The combination of the two methodologies is more useful than the isolated use of either approach.
the area and soft-ware was developed to analyze MCD data.MOH should start the development of data bases for MCD, make them available, and include the highlights in the MOH annual reports.Special reports discussing individual disease conditions particularly circulatory, neoplasms, ill-defined and respiratory conditions need to be organized for Kuwait.

Table 1
. The causes entered as the UCD, as second, third, fourth or higher cause and their relative contribution is shown in the table; here the % is computed for the valid cases.The row assigned missing in the table denotes the number for which a lower number of causes were entered.With the UCD the total is 7966, since every case had an UCD; with the column 2nd cause the number dropped to 7430, since in 536 cases only the underlying cause was mentioned on the DC; and with the group in which a 3rd cause was found the total came to 6294.The total number of entries amounted to 28982.The circulatory system diseases were reported in 51.0% of the UCD, and were more prominent as a second cause of death accounting for 78.8%.The proportion dropped to 20.7%as a third cause.The total entries for circulatory system amounted to 13799; this is the number of times they were noted on the death certificates including the UCD.

Table 3 .
Ratios were computed by dividing the MCD by the number of the UCD.The