Sofiane Kab

Epidemiology of Parkinson's disease

Parkinsons disease (PD) is the second most common neurodegenerative disease after Alzheimers. PD is considered a multifactorial disorder that results, in most cases, from the combined effects of multiple risk and protective factors, including genetic and environmental ones. This review discusses some of the methodological challenges involved in assessing the descriptive, prognostic and etiological epidemiological studies of PD, and summarizes their main findings.

Parkinson disease male-to-female ratios increase with age: French nationwide study and meta-analysis

Background Parkinson’s disease (PD) is 1.5 times more frequent in men than women. Whether age modifies this ratio is unclear. We examined whether male-to-female (M–F) ratios change with age through a French nationwide prevalence/incidence study (2010) and a meta-analysis of incidence studies. Methods We used French national drug claims databases to identify PD cases using a validated algorithm. We computed M–F prevalence/incidence ratios overall and by age using Poisson regression. Ratios were regressed on age to estimate their annual change. We identified all PD incidence studies with age/sex-specific data, and performed a meta-analysis of M–F ratios. Results On the basis of 149 672 prevalent (50% women) and 25 438 incident (49% women) cases, age-standardised rates were higher in men (prevalence=2.865/1000; incidence=0.490/1000 person-years) than women (prevalence=1.934/1000; incidence=0.328/1000 person-years). The overall M–F ratio was 1.48 for prevalence and 1.49 for incidence. Prevalence and incidence M–F ratios increased by 0.05 and 0.14, respectively, per 10 years of age. Incidence was similar in men and women under 50 years (M–F ratio <1.2, p>0.20), and over 1.6 (p<0.001) times higher in men than women above 80 years (p trend <0.001). A meta-analysis of 22 incidence studies (14 126 cases, 46% women) confirmed that M– F ratios increased with age (0.26 per 10 years, p trend=0.005). Conclusions Age-increasing M–F ratios suggest that PD aetiology changes with age. Sex-related risk/protective factors may play a different role across the continuum of age at onset. This finding may inform aetiological PD research.

Association of UV radiation with Parkinson disease incidence: A nationwide French ecologic study

Background: Vitamin D is thought to contribute to brain health, but it is unclear whether low vitamin D levels are associated with increased incidence of Parkinsons disease (PD). Using ultraviolet B (UV‐B) as a surrogate for vitamin D levels, we conducted a nationwide ecologic study in France in order to examine the association of UV‐B with PD incidence. Methods: We used French national drug claims databases to identify PD cases using a validated algorithm. UV‐B data from the solar radiation database were derived from satellite images. We estimated PD incidence (2010–2012) at the canton level (small administrative French unit) and used multilevel Poisson regression to examine its association with UV‐B (2005 annual average), after adjustment for age, sex, deprivation index, density of neurologists, smoking, proportion of agricultural land, and vitamin D supplementation. Results: Analyses are based on 69,010 incident PD patients. The association between UV‐B and PD incidence was quadratic (P<0.001) and modified by age (P<0.001). Below 70y, incidence was higher in the bottom quintile (relative risk, RRQ1:45‐49y=1.18, 95% CI=1.08–1.29) compared with the middle UV‐B quintile, and lower in the top quintile (RRQ5:45‐49y=0.85 [0.77–0.94]). An opposite pattern was observed in older subjects (RRQ1:85‐89y=0.92 [0.89–0.96]; RRQ5:85‐89y=1.06 [1.02–1.11]). Analysis based on continuous UV‐B yielded similar conclusions. Conclusions: In this nationwide study, there was an age‐dependent quadratic association between UV‐B and PD incidence. This study suggests that reasonable UV‐B exposure is associated with lower PD risk in younger persons and that future studies should examine dose‐response relations and take age into account. HighlightsThere is an age‐dependent quadratic association between UV‐B and PD incidence.Reasonable UV‐B exposure is beneficial in younger persons for the risk of PD.Our findings are consistent with a role of vitamin D in PD, especially at younger ages.Future studies should examine dose‐effect relations and take age into account.

Nationwide incidence of motor neuron disease using the French health insurance information system database

Abstract Objective: There are no estimates of the nationwide incidence of motor neuron disease (MND) in France. We used the French health insurance information system to identify incident MND cases (2012–2014), and compared incidence figures to those from three external sources. Methods: We identified incident MND cases (2012–2014) based on three data sources (riluzole claims, hospitalisation records, long-term chronic disease benefits), and computed MND incidence by age, gender, and geographic region. We used French mortality statistics, Limousin ALS registry data, and previous European studies based on administrative databases to perform external comparisons. Results: We identified 6553 MND incident cases. After standardisation to the United States 2010 population, the age/gender-standardised incidence was 2.72/100,000 person-years (males, 3.37; females, 2.17; male:female ratio = 1.53, 95% CI1.46–1.61). There was no major spatial difference in MND distribution. Our data were in agreement with the French death database (standardised mortality ratio = 1.01, 95% CI = 0.96–1.06) and Limousin ALS registry (standardised incidence ratio = 0.92, 95% CI = 0.72–1.15). Incidence estimates were in the same range as those from previous studies. Conclusions: We report French nationwide incidence estimates of MND. Administrative databases including hospital discharge data and riluzole claims offer an interesting approach to identify large population-based samples of patients with MND for epidemiologic studies and surveillance.

Farming and incidence of motor neuron disease: French nationwide study

The association of farming with motor neuron disease (MND) is unclear, with conflicting studies. We performed a French nationwide study of the association of farming with MND incidence, and compared findings with those for Parkinsons disease (PD), which has been shown to be more frequent in farmers.

Association of Parkinson’s disease with industry sectors: a French nationwide incidence study

In order to identify working environments at risk for Parkinson’s disease (PD), we investigated the relation between the importance of industry sectors, used as a surrogate for occupational exposures, and PD incidence in French cantons. The number of incident PD cases (2010–2014) in 3689 cantons of metropolitan France was determined using drug claims from French National Health Insurance databases. The proportions of workers in 38 industry sectors in 2006 were calculated for each canton. Associations between the proportions of workers in industry sectors and PD age/sex-standardized incidence ratios were examined using incidence rate ratios (IRR) and 95% confidence intervals (CI) estimated with multilevel negative binomial regressions with a random intercept at the canton-level and adjusted for smoking, deprivation index, and density of neurologists. We then used two-step semi-Bayes hierarchical regression (HR) to include prior information about exposure to pesticides, metals, and solvents in each industry sector. We identified 112,625 incident cases. PD incidence was higher in areas characterized by high proportions of workers in “Agriculture, forestry and fishing” (IRRHR = 1.042; CI 95% = 1.014–1.070; p-TrendHR = 0.004), “Manufacture of textiles, wearing apparel, leather and related products” (IRRHR = 1.024; CI 95% = 1.005–1.044; p-TrendHR = 0.010), and “Manufacture of basic metals and fabricated metal products, except machinery and equipment” (IRRHR = 1.024; CI 95% = 1.003–1.046; p-TrendHR = 0.071). This nationwide study, based on a comprehensive analysis of industry sectors, shows significant associations between high proportions of workers in specific industry sectors (agriculture, metallurgy, textile) and PD incidence that may be targeted in further epidemiological studies to replicate and better understand these associations.

Age-dependent sex ratios of motor neuron disease: French nationwide study and meta-analysis

Objective To examine the relation of age with male-to-female (M/F) ratios and incidence rates of motor neuron disease (MND) in a French nationwide study and meta-analysis of incidence studies. Methods We used data from the French National Health Insurance databases. Patients with incident MND (2010–2014) were identified based on drug claims (riluzole), hospitalization records, death records, and long-term chronic disease benefits. We estimated age-specific M/F incidence ratios using Poisson regression. Poisson, Gompertz, and multistep models were used to model the relation between age and incidence. We performed a meta-analysis (n = 28 studies) and used meta-regression to examine the relation of age with incidence rates and ratios. Results In France, we identified 10,848 patients with incident MND (6,021 men, 4,827 women). Incidence was higher in men than in women in all age groups. M/F ratios were significantly different across age groups and followed a quadratic trend (p < 0.001). Between 20 and 49 years, the average M/F ratio was 2.26 (95% confidence interval [CI] = 1.96–2.62); it was 1.41 (95% CI = 1.35–1.47) between 50 and 84 years, and 1.88 (95% CI = 1.64–2.17) after 85 years. Incidence was lower in women than men at younger ages, but increased more steeply in women than men. Similar patterns were observed in the meta-analysis of incidence studies, especially in 19 higher-quality studies. Conclusion The relation between age and M/F incidence ratios of MND follows a quadratic U-shaped pattern with an abrupt drop after the fifth decade. The change in M/F ratios before and after menopause suggests that reproductive/hormonal protective factors have a role in women and should prompt further studies to explore this hypothesis.