Childhood leukaemia incidence and trends in a Middle Eastern country during 1980-2014: a population-based study.

BACKGROUND: This retrospective cohort study examines the trends in childhood leukaemia age-standardized incidence rates (ASIRs) (per million person-years) using cases which were diagnosed at age 0-19 years from 1980 to 2014 and recorded in the Kuwait Cancer Control Center (KCCC) registry. METHODS: Childhood leukaemia age-specific incidence rates overall and by sub-cohorts defined by age (0-4, 5-9, 10-14, and 15-19 years), sex (male, female) and nationality (Kuwaiti, non-Kuwaiti) were computed and age-standardized. Joinpoint regression models were used to evaluate trends in childhood leukaemia ASIRs. Average annual percent change (AAPC) and its 95% confidence interval (CI) were used to interpret the observed trends. RESULTS: During the study period, 1077 childhood leukaemia cases of 32.3 million person-years were diagnosed. From 1980 to 2014, the average annual childhood leukaemia ASIR was 53.1 (95% CI 20.9, 85.2). Overall childhood leukaemia ASIRs significantly decreased on average by 6.8% per year (AAPC = -6.8; 95% CI -12.1, -1.1; p = 0.02) from 1980 to 1993, but a marginally significant increase in ASIRs from 1993 to 2014 was recorded (AAPC = 2.5; 95% CI -0.5, 5.5; p = 0.10). During the entire period, childhood leukaemia ASIRs trends significantly (p < 0.05) increased among 6 of 16 sub-cohorts, which was more pronounced among females and 10-14-year-old children. CONCLUSIONS: Overall, ASIRs significantly increased from 1993 to 2014, which specifically seems to be driven by an increase in ASIRs among females and 10-14 -year-old children. These increasing trends underscore the potential involvement of a range of exposures. Future studies on unravelling such factors may help develop preventive measures to minimize childhood leukaemia risk in this and similar settings in the region.

Joinpoint Regression Analysis of Trends in Multiple Sclerosis Incidence in Kuwait: 1980-2019.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system with unknown precise etiology. Temporally, a tendency for increasing MS incidence has been recorded worldwide. This cross-sectional cohort study sought to quantify trends in the age-standardized incidence rates (ASIRs) (per million person-years) of MS in Kuwait from 1980 to 2019, overall and by subcohorts defined by age at MS onset, sex, and nationality. METHODS: MS incidence data from 1980 to 2019 were obtained from the Kuwait National MS Registry (KNMSR). Using midyear relevant Kuwait population as denominator and the World Standard Population as a reference, MS ASIRs overall and by subcohorts defined by age at onset (0-19, 20-39, and 40+ years), sex (male and female), and nationality (Kuwaiti and non-Kuwaiti) were computed. Joinpoint regression analysis was conducted to estimate average annual percent change (AAPC) and its 95% confidence interval (CI) overall and by subcohorts. RESULTS: During 1980-2019, a total of 1,764 MS incident cases of 95.6 million person-years at-risk were diagnosed and registered in KNMSR. The overall MS ASIR (per million person-years) during the study period was 34.1 (95% CI: 16.1, 52.1). Between 1980 and 2010, in the total cohort, ASIRs of MS significantly increased by 13% (AAPC = 13.0; 95% CI: 10.8, 15.3; p < 0.001), followed by statistically nonsignificant declining trend during the ensuing period (AAPC = -3.8; 95% CI: -14.8, 8.8; p = 0.522). Joinpoint regression analysis revealed that 2 subcohorts of Kuwaiti females each with one joinpoint had significant increasing trends in MS ASIRs (0- to 19-year-old Kuwaiti females, AAPC: 1980-2009, 81.0; 95% CI: 58.2, 107.0; p = 0.001; 20- to 39-year-old Kuwaiti females, AAPC: 1980-1999, 131.7; 95% CI: 26.9, 322.8; p = 0.021). Additionally, of remaining 10, 6 subcohorts had significantly (p < 0.05) increasing trends in MS ASIRs from 1980 to 2019. CONCLUSIONS: From 1980 to 2010, Kuwait has an overall significantly increasing trend in MS ASIRs followed by a nonsignificant declining drift in the ensuing period. The increasing trend in MS risk appeared to be driven by increased risk among Kuwaiti females younger than 40 years. The underlying factors modulating MS risk in Kuwait need further studies.

Chronic urinary tract infection and bladder carcinoma risk: a meta-analysis of case-control and cohort studies.

OBJECTIVE: This meta-analysis of published case-control and cohort studies sought to quantify the magnitude and direction of association between chronic UTI (defined as the infection of the urinary tract that either does not respond to treatment or keeps recurring) and risk of bladder carcinoma (BCa) (i.e., including mainly urothelial carcinoma, squamous cell carcinoma or adenocarcinoma). METHODS: A literature search was conducted using Medline, Embase, Ovid, Web of Science, Science Direct and Cochrane Library, which was supplemented with manual search of reference lists of the identified articles. Case-control and cohort studies examining UTI as a predictor of BCa risk published through June 2016 were eligible. Using random-effects models, odds ratios (OR) or relative risks (RR) from eligible studies were combined to synthesize summary effect estimates. The included studies were assessed for methodological quality and potential publication bias. Heterogeneity by study characteristics was examined by sub-group and meta-regression analyses. RESULTS: Eighteen case-control and three cohort studies published between 1963 and 2016 were eligible. Random-effects models showed that UTI was significantly associated with an increased BCa risk both in case-control studies (summary ORRE = 2.33; 95% CI 1.86, 2.92) and cohort studies (summary RRRE = 2.88; 95% CI 1.20, 6.89). The observed relationship of UTI with an increased BCa risk was independent of the study characteristics considered. No significant publication bias was detected. CONCLUSIONS: Chronic UTI was significantly and independently associated with an increased BCa risk. However, due to the presence of high between-study heterogeneity and inconsistent patterns of adjusted confounding effects, more data are needed to clarify the role of chronic UTI in causation of BCa and if established, prompt and effective treatment of UTI may minimize a substantial proportion of BCa risk.

Age-Period-Cohort Modeling of Multiple Sclerosis Incidence Rates in Kuwait: 1980-2014.

BACKGROUND: Multiple sclerosis (MS) is a complex immune-mediated disorder of the central nervous system with undefined etiology. Genetic predisposition and environmental factors play an imperative role in MS causation and its sustained increasing burden worldwide. This study examined the age, period, and cohort effects on MS incidence rates in Kuwait. METHODS: In this retrospective cohort study, data on MS cases diagnosed between January 1, 1980 and December 31, 2014 and registered in National MS Registry and reference population were obtained. Age-period-cohort (APC) analysis was conducted using a loglinear Poisson regression model to supplement the descriptive and graphical presentation. Descriptive statistics were complemented with APC parameters' estimates including net drift, local drift, age at onset curve, and longitudinal age trend. Age effect was presented as incidence rates (per 105 person-years), whereas period and cohort effects were presented as adjusted relative rates. RESULTS: A total of 1,131 cases were diagnosed in 1,385,923 person-years. Overall age-standardized MS incidence rate was 64.5 (95% CI 52.4-79.8). An estimated annual percentage change revealed 7.4% annual increase in MS incidence rate during the study period (Net drift = 7.4%; 95% CI 4.1-10.8%). APC "fitted" age-at-onset curve showed a bimodal pattern with peaked incidence rates at 20-24 years and 45-49 years of age. Compared with the referent period (1980-1984) and cohort (1970-1974), MS incidence rates progressively and significantly (p < 0.001) increased during subsequent time periods and in successive cohorts. Results of APC analysis are descriptive in nature and specific etiological hypotheses were not evaluated. However, the findings of this study substantiated the notion of multiplicity of genetic and/or environmental risk factors' contributions. CONCLUSION: A substantial increase in MS incidence rates was recorded, which significantly varied in all 3 temporal dimensions during the study period. Future studies may contemplate biological basis for recorded temporal increase in MS risk.

Month of birth and risk of multiple sclerosis in Kuwait: a population-based registry study.

BACKGROUND: Multiple sclerosis (MS) is a complex immune-mediated disorder of central nervous system with undefined etiology. This study examined the month of birth effect on subsequent MS risk later in the life in Kuwait. METHODS: The month of birth of MS patients enrolled in Kuwait MS Registry between 1 January 1950-30 April 2013 was compared with the month of births in the general population during the comparable period. Multivariable log-linear Poisson regression model was used to analyze the data. RESULTS: Data on 1035 confirmed MS patients were collected, of which 65.2% were female and 77.1% were Kuwaiti. The overall risk of MS births (per 10(5) births in general population) was 28.5 (95% confidence interval (CI): 26.8-30.3). Multivariable log-linear Poisson regression model showed a significant (p=0.004) peak in the number of MS births during December (θo=340(o)). During this month, the risk of MS birth was 1.3 times the risk of MS birth in the trough month after adjusting for the effects of gender and nationality (adjusted relative risk=1.3; 95% CI: 1.1-1.6). The amplitude (α±standard deviation: 0.13±0.014) of sinusoidal curve showed a significant (p=0.004) difference of 13% from the mean to maximum MS births during peak month. CONCLUSIONS: This study showed a statistically significant month of birth effect on MS risk with 13% excess MS births during December in Kuwait. Future studies may contemplate ascertaining the seasonal factors eliciting the observed association. The insight gained by unraveling such factors may help curtail MS risk in this and other similar settings in the region.

Non-parametric analysis of seasonality in birth and multiple sclerosis risk in second generation of migrants in Kuwait.

BACKGROUND: There are inconsistent reports about multiple sclerosis (MS) risk among migrants from low to high MS risk geographical regions. This study assessed the overall MS incidence and evaluated seasonality in birth and subsequent MS risk later in the life in second generation of migrants born and lived in Kuwait. METHODS: We assessed the overall and gender-specific MS risk in second generation of migrants born and lived in Kuwait between January 1, 1950 and April 30, 2013. Data on migrants' MS patients diagnosed and registered in Kuwait National MS Registry were used. Hewitt's non-parametric test was carried out to evaluate the seasonality in migrants' MS births in comparison with the second generation migrants' births in general population. RESULTS: During the study period, an overall risk of migrants' MS births (per 100,000 non-Kuwaiti births in general population) was 23.8 (95% CI: 20.8 - 27.0). Gender-specific MS risk showed that non-Kuwaiti female had statistically significant (p = 0.003) higher risk (28.6; 95% CI: 24.2 - 33.7) than non-Kuwaiti males (18.7; 95% CI: 15.1-23.0). The month-specific distribution of migrants' MS births compared with migrants' births in general population did not differ significantly (χ2 goodness-of-fit test statistic = 9.51, p = 0.575). Hewitt's non-parametric test revealed an evidence of slight but statistically non-significant (p = 0.090) increased tendency of migrants' MS births during September through February. CONCLUSIONS: The proportion of migrants' MS births (per 100,000 migrants' births in general population) over the study period was 23.8 (95% CI: 20.8 - 27.0), which was statistically significantly higher than the previously reported Kuwaiti national MS births (16.2; 95% CI: 15.1-17.4) in Kuwait. Non-parametric analysis showed slight but statistically non-significant increased tendency of migrants' MS births from September through February. Knowledge of MS risk factors and how and when they act among genetically vulnerable individuals from gestation to early adulthood will help design prevention strategies.