Design: Prospective double blind cohort study.

Setting: Diving clubs around Heidelberg and departments of neuroradiology and neurology.

Subjects: 87 sport divers with a minimum of 160 scuba dives (dives with self contained underwater breathing apparatus).

Main outcome measures: Presence of multiple brain lesions visualised by cranial magnetic resonance imaging and presence and size of patent foramen ovale as documented by echocontrast transcranial Doppler ultrasonography.

Results: 25 subjects were found to have a right-to-left shunt, 13 with a patent foramen ovale of high haemodynamic relevance. A total of 41 brain lesions were detected in 11 divers. There were seven brain lesions in seven divers without a right-to-left shunt and 34 lesions in four divers with a right-to-left shunt. Multiple brain lesions occurred exclusively in three divers with a large patent foramen ovale (P=0.004).

Conclusions: Multiple brain lesions in sport divers were associated with presence of a large patent foramen ovale. This association suggests paradoxical gas embolism as the pathological mechanism. A patent foramen ovale of high haemodynamic relevance seems to be an important risk factor for developing multiple brain lesions in sport divers.

Department of Neuroradiology,
University of Heidelberg,
Klinikum Heidelberg,
Im Neuenheimer Feld 400,
D 69120 Heidelberg,
Germany
Michael Knauth, neuroradiologist
Tina Kerby, technician
Michael Forsting, neuroradiologist
Klaus Sartor, neuroradiologist

Department of Neurology,
University of Heidelberg,
Klinikum Mannheim,
Germany
Stefan Ries, neurologist
Michael Daffertshofer, neurologist
Michael Hennerici, neurologist

Department of Biology,
University of Frankfurt,
Klinikum Frankfurt,
Germany
Stefan Pohimann, biologist

Correspondence and reprint requests to: Dr Knauth.

Design: Analysis of mortality for adults aged 20-69 in 1970-2 and 1989-92 using population data from 1971 and 1991 censuses. Mortality of Scottish and Irish immigrants aged 25-74 was also compared with mortality in Scotland and Ireland for 1991.

Setting: England and Wales.

Main outcome measures: Standardised mortality ratios for deaths from all causes, ischaemic heart disease, cerebrovascular disease, lung cancer, and breast cancer.

Results: In 1989-92 mortality from all causes was higher than the national average for Scottish immigrants, by 32% for men and 36% for women; for Irish immigrants it was higher by 39% for men and 20% for women; and for Caribbean born men it was lower by 23%. Ischaemic heart disease and lung cancer accounted for 30-40% of the excess mortality in Scottish and Irish immigrants. For south Asians, excess mortality from circulatory disease was balanced by lower mortality from cancer. Standardised mortality ratios for cerebrovascular disease in 1989-92 were highest for west African immigrants (271 for men and 181 for women).

Conclusions: Widening differences in mortality ratios for migrants compared with the general population were not simply due to socioeconomic inequalities. The low mortality from all causes for Caribbean immigrants could largely be attributed to low mortality from ischaemic heart disease, which is unexplained. The excess mortality from cerebrovascular and hypertensive diseases in migrants from both west Africa and the Caribbean suggests that genetic factors underlie the susceptibility to hypertension in people of black African descent.

Epidemiology Unit,
Department of Epidemiology and Population Sciences,
London School of Hygiene & Tropical Medicine,
London,
WC1E 7HT
Sarah Wild, Wellcome training fellow in clinical epidemiology
Paul McKeigue, senior lecturer

Correspondence to: Dr Wild.

Design: Poisson regression modelling using data from death certificates, censuses, and national travel surveys.

Setting: England and Wales.

Subjects: Resident children aged 0-14.

Main outcome measures: Deaths from unintentional injury and poisoning.

Results: Child deaths from injury declined by 34% (95% confidence interval 28% to 40%) per 100,000 population between 1985 and 1992. Substantial decreases in each of the leading causes of death from injury contributed to this overall decline. On average, children walked and cycled less distance and travelled substantially more miles by car in 1992 compared with 1985. Deaths from road traffic accidents declined for pedestrians by 24% per mile walked and for cyclists by 20% per mile cycled, substantially less than the declines per 100 000 population of 37% and 38% respectively. In contrast, deaths of occupants of motor vehicles declined by 42% per mile travelled by car compared with a 21% decline per 100 000 population.

Conclusions: If trends in child mortality from injury continue the government's target to reduce the rate by 33% by the year 2005 will be achieved. A substantial proportion of the decline in pedestrian traffic and pedal cycling deaths, however, seems to have been achieved at the expense of children's walking and cycling activities. Changes in travel patterns may exact a considerable price in terms of future health problems.

Child Health Monitoring Unit,
Department of Epidemiology and Biostatistics,
Institute of Child Health, University of London,
London WC1N 1EH
Carolyn DiGuiseppi, senior clinical research fellow
Ian Roberts, senior lecturer
Leah Li, medical statistician

Correspondence to: Dr DiGuiseppi.