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Alfred Spira

Publications and source records attributed to Alfred Spira.

7 recordsLinked to original sources
PubMed2006

Male gonadal dose of ionizing radiation delivered during X-ray examinations and monthly probability of pregnancy: a population-based retrospective study.

BACKGROUND: Male gonadal exposure to ionizing radiation may disrupt spermatogenesis, but its influence on the fecundity of couples has been rarely studied. We aimed to characterize the influence of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy. METHODS: We recruited a random sample of women who retrospectively described 1110 periods of unprotected intercourse beginning between 1985 and 1999 and leading either to a live birth or to no pregnancy; their duration was censored after 13 months. The male partner answered a telephone questionnaire on radiodiagnostic examinations. We assigned a mean gonadal dose to each type of radiodiagnostic examination. We defined male dose for each period of unprotected intercourse as the sum of the gonadal doses of the X-ray examinations experienced between 18 years of age and the date of discontinuation of contraception. Time to pregnancy was analysed using a discrete Cox model with random effect allowing to estimate hazard ratios of pregnancy. RESULTS: After adjustment for female factors likely to influence fecundity, there was no evidence of an association between male dose and the probability of pregnancy (test of homogeneity, p = 0.55). When compared to couples with a male gonadal dose between 0.01 and 0.20 milligrays (n = 321 periods of unprotected intercourse), couples with a gonadal dose above 10 milligrays had a hazard ratio of pregnancy of 1.44 (95% confidence interval, 0.73-2.86, n = 31). CONCLUSION: Our study provides no evidence of a long-term detrimental effect of male gonadal dose of ionizing radiation delivered during radiodiagnostic on the monthly probability of pregnancy during the year following discontinuation of contraceptive use. Classification errors due to the retrospective assessment of male gonadal exposure may have limited the statistical power of our study.

Adult↗
PubMed2005

Were less disabled patients the most affected by 2003 heat wave in nursing homes in Paris, France?

OBJECTIVE: To analyse the change of mortality rates (MRs) and their contributing medical factors among nursing home patients during the 2003 heat wave in France. METHODS: A retrospective observational study was conduced in all nursing homes of the Assistance-Publique-Hôpitaux de Paris (AP-HP), the French largest public hospital group. All AP-HP nursing home patients (4,403) who were institutionalized in May, 2003, were concerned. The MRs of patients between three periods (before, during and after the August 2003 heat wave period) were compared according to their demographic characteristics, level of dependence and medical condition. RESULTS: The MR increased from 2.2 per cent persons month (ppm) (1.9-2.4) before heat wave up to 9.2 ppm (8.0-10.4) during heat wave and back to 2.4 ppm (2.2-2.7) after heat wave. MRs before heat wave were higher among highly dependent patients compared to those less dependent [mortality rate ratio (MRR) = 2.66 (1.69-4.21)]. This difference disappeared during the heat wave [MRR = 1.28 (0.91-1.81)] and appeared again after heat wave [MRR = 2.21 (1.52-3.23)]. The same pattern was observed for several medical conditions, such as severe malnutrition or swallowing disorders. CONCLUSION: These results suggest that medical care during heat wave has been directed towards more fragile patients, helping to limit deaths in this group. Less frail patients made the largest contribution to excess mortality during the heat wave. During extreme weather conditions, specific attention should be paid not only to frail persons, but to all the elderly community.

Aged↗
PubMed2004

[Prevention in France, 2004: first elements for reflection].

Prevention has been underdeveloped in the public health arena, at least in France. It is a complex discipline, relying both on strong scientific methodology as well as social and economical considerations, which may be sometimes a source of conflicts.

France↗
PubMed2004

How would a decline in sperm concentration over time influence the probability of pregnancy?

BACKGROUND: Reports have suggested a decline in sperm concentration during the second half of the 20th century. The effect of this decline on fecundability (the monthly probability of pregnancy) could be detected in principle by a study of time to pregnancy. In practice, the amplitude of this expected effect is not well known and the statistical power of time-to-pregnancy studies to detect it has not been explored. METHODS: We developed a nonparametric model to describe a temporal decline in sperm concentration using data on French semen donors. We then applied this model to 419 Danish couples planning a first pregnancy in 1992, to predict their time to pregnancy as if the pregnancy attempt had begun during earlier decades with higher sperm concentrations. Finally, we used bootstrap simulations to estimate the statistical power of prospective or retrospective studies that compared fecundability (estimated from time to pregnancy) across these time periods. We express the change in fecundability over time as a fecundability ratio (FR), with values less than 1 indicating decreased fecundability. RESULTS: We estimate that the median sperm concentration decreased by 21% from 1977 to 1992 and by 47% from 1947 to 1992. The estimated decline in fecundability with those semen changes was 7% from 1977 to 1992 (FR = 0.93, adjusted) and 15% from 1947 to 1992 (FR = 0.85, adjusted). The total numbers of couples that would be needed in prospective studies of time to pregnancy to detect these changes in fecundability (with a power of 80%) were 12,000 when comparing 1977 to 1992, and 2000 when comparing 1947 to 1992. Retrospective studies of the same size that excluded childless couples had much lower statistical power and were biased toward the null. CONCLUSION: The effect of realistic declines in sperm concentration on time to pregnancy may be observed only with studies that include several thousand couples.

Adult↗
PubMed2003

Does male age affect the risk of spontaneous abortion? An approach using semiparametric regression.

Couples in industrialized countries tend to delay attempting to have children, which may lower their chances of livebirth. The authors assessed the association between male age and the risk of spontaneous abortion between weeks 5 and 20 of pregnancy, controlling for female age. They interviewed by telephone a random cross-sectional population of 1,151 French women who had been pregnant between 1985 and 2000 (participation rate, 73%). A total of 12.2% of the 2,414 pregnancies resulted in spontaneous abortion. Semiparametric regression was used to define a discrete time survival model with a random effect taking into account induced abortions, in which female age was coded by a third-degree polynomial. This final model predicted that the risk (rate ratio) of spontaneous abortion was 2.13-fold higher for women age 25 years whose partner was age 35 years or older than for women age 25 years whose partner was younger than age 35 years (95% confidence interval: 1.07, 4.26). No such increased risk of spontaneous abortion with male age was estimated when the woman was age 35 years (rate ratio = 0.61, 95% confidence interval: 0.35, 1.07). Thus, increasing male age could increase the risk of spontaneous abortion when the female partner is less than 30 years of age.

Abortion, Spontaneous↗