BMJ 2001;323:1035-1036 ( 3 November )



Papers


Social deprivation in Duchenne muscular dystrophy: population based study

Kate Bushby, professor of neuromuscular genetics a, Simon Raybould, senior
research associate b, Sara O'Donnell, medical student c, James G Steele,
senior lecturer d.
a Institute of Human Genetics, International Centre for Life, Newcastle upon
Tyne NE1 3BZ, b Centre for Urban and Regional Development Studies,
University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, c Medical
School, University of Newcastle upon Tyne, Newcastle upon Tyne NE2 4BW, d
Department of Restorative Dentistry, University of Newcastle upon Tyne,
Newcastle upon Tyne NE2 4BW
Correspondence to: K Bushby [log in to unmask]
<mailto:[log in to unmask]>
Duchenne muscular dystrophy is an X linked disorder affecting approximately
1 in 3500 male live births. The incidence remains stable in most
populations, maintained by a high rate of new mutations in the dystrophin
gene. 1 <http://bmj.com/cgi/content/full/323/7320/#B1>  We observed that a
higher than expected proportion of families of patients with Duchenne
muscular dystrophy seemed to be from a deprived background, even at the time
of first diagnosis (usually by age 5). We measured the level of material
deprivation based on the place of residence at the time of diagnosis of all
patients with Duchenne muscular dystrophy in the north of England to test
the hypothesis that this single gene disorder is associated with social
deprivation.




  Participants, methods, and results
Records of children with Duchenne muscular dystrophy in the Northern region
of England have been scrupulously maintained since the 1960s, and we believe
that ascertainment in the region is complete. We analysed data from the
whole group of families with Duchenne muscular dystrophy in the region and
also subdivided the group into four categories according to the origin of
the mutation in the family (table).



View this table:
[in this window] <http://bmj.com/cgi/content/full/323/7320/1035/Fu1>
[in a new window] <http://bmj.com/cgi/content-nw/full/323/7320/1035/Fu1>

Townsend scores of enumeration districts with and without families with
Duchenne muscular dystrophy
In all, 229 of the 246 families with children diagnosed as having Duchenne
muscular dystrophy between 1967 and 1999 in the Northern region had valid
postcodes available at diagnosis. We linked patients' postcodes to data from
the latest national census by using the central postcode directory, which
provides a link between postcodes and enumeration districts consisting of
100-150 households. No enumeration district contained more than one affected
family, and each family was counted as a single case irrespective of the
number of boys affected.
We used a non-parametric test (Mann-Whitney U test) to compare the Townsend
scores 2 <http://bmj.com/cgi/content/full/323/7320/#B2>  for enumeration
districts in which cases of Duchenne muscular dystrophy occurred against all
enumeration districts in the region without cases, for all cases and for the
four subgroups. We then used Monte Carlo analysis to compare the mean and
distribution of scores for the enumeration districts of all affected
families with the distribution of Townsend scores derived from repeated
random samples of enumeration districts.
The results (table) show large and significant differences between the
Townsend scores of affected families and Townsend score distributions for
the rest of the population (corrected for the number of children aged 5 and
under). The differences occurred in all of the subgroups. The Monte Carlo
analysis confirmed the difference between affected families and the rest of
the population---the mean Townsend score for the affected boys was at least
2.5 standard deviations greater than that for the random control groups in
every iteration.




  Comment
As a group, patients with Duchenne muscular dystrophy have significantly
greater material deprivation at diagnosis than the average of the population
from which they are drawn. This is evident even in families where the
disease is known to be the result of a new mutation. We can find no simple
explanation for this effect, but it seems that new mutations in the
dystrophin gene do not occur randomly in the population. The rate of new
germline mutations in the dystrophin gene is particularly high, 1
<http://bmj.com/cgi/content/full/323/7320/#B1>  and the mechanisms by which
these mutations occur are poorly understood. Further studies are needed to
determine what aspects or covariates of deprivation may contribute to this
effect and whether this ecological association occurs for other genes with a
high level of new mutations.
Patients from deprived backgrounds have less access to health care than
people from more affluent areas, 3
<http://bmj.com/cgi/content/full/323/7320/#B3>  4
<http://bmj.com/cgi/content/full/323/7320/#B4>  and diagnosis of Duchenne
muscular dystrophy is often delayed. 5
<http://bmj.com/cgi/content/full/323/7320/#B5>  Children with Duchenne
muscular dystrophy have a lifelong need for the highest quality of care, and
the relatively high levels of deprivation associated with the disease may
restrict availability of the sustained, high quality, specialised support
needed.



  Acknowledgments
Angela Hill provided much of the inspiration for this work. We thank Dr
Louise Parker for helpful comments.
Contributors: KB oversaw the project and cowrote the paper. She is the
guarantor. SR analysed the data. SO'D collected and processed the data. JGS
contributed to developing the hypothesis and cowrote the paper.

  Footnotes
Funding: The Newcastle Muscle Centre receives financial support from the
Muscular Dystrophy Campaign.
Competing interests: None declared.
Further details of methods are on the BMJ's website



  References


1.
Gorospe JR, Hoffman EP. Duchenne muscular dystrophy. Curr Opin Rheumatol
1992; 4: 794-800 [Medline]
<http://bmj.com/cgi/external_ref?access_num=1457273&link_type=MED> .
2.
Townsend P, Phillimore P, Beattie A. Health and deprivation: inequality and
the north. London: Croom Helm, 1988
3.
Benzeval M, Judge K. Access to healthcare in England: continuing
inequalities in the distribution of general practitioners. J Pub Health Med
1996; 18: 33-40 [Medline]
<http://bmj.com/cgi/external_ref?access_num=8785073&link_type=MED> .
4.
Acheson D. Independent enquiry into inequalities in health. London:
Stationery Office, 1998.
5.
Bushby K, Hill A, Steele JG. Failure of early diagnosis in symptomatic
Duchenne muscular dystrophy. Lancet 1999; 353: 557-558 [Medline]
<http://bmj.com/cgi/external_ref?access_num=10028989&link_type=MED> .
(Accepted 11 July 2001)


Edward E. Rylander, M.D.
Diplomat American Board of Family Practice.
Diplomat American Board of Palliative Medicine.