Social Determinants in Chronic Disease in British Columbia
Condition: Cystic Fibrosis; Diabetes Mellitus Type I; Chronic Renal Insufficiency
MeSH terms: Cystic Fibrosis; Renal Insufficiency; Renal Insufficiency, Chronic; Diabetes Mellitus; Diabetes Mellitus, Type 1; Fibrosis
Study type: Observational

Summary: 
      Anyone who practices clinical medicine will understand that socially disadvantaged children
      will have worse health outcomes, no matter what the underlying condition might be. There is
      limited prospective data on the effects of social deprivation on children in BC and there is
      none concerning the effects of social deprivation on children with chronic diseases. In order
      to generate relevant data for those who manage children with chronic diseases in BC, the
      investigators wish to perform an observational study of the relationship between
      questionnaire-derived social variables and measured outcomes in children with cystic
      fibrosis, type 1 diabetes, and chronic kidney disease.

      Our working hypothesis is that there is an association between social determinants of health
      (income, education, race) and health outcomes in children with cystic fibrosis, type 1
      diabetes and chronic renal failure, that is independent of access to health care (assessed by
      distance to nearest specialty clinic and number of clinic visits in the last year).
    

Detailed description: 
      1. Cystic fibrosis (CF). Cystic fibrosis is a genetic condition that causes slowly
           progressive lung disease. It occurs in people of all social class so the disease itself
           is independent of social factors. There is considerable variation in the outcome of CF
           in different children. There are many potential causes for these differences but the
           available literature would suggest that a significant part of this variability is due to
           social factors. While there are no prospective clinical studies, the limited information
           from database reviews suggest that socially deprived children have significantly worse
           outcomes. In the US, children living in poverty are twice as likely to be underweight
           and over three times more likely to die (25). UK data is similar - disadvantaged
           children have worse growth parameters and lower lung function compared to richer
           children (26).

        2. Type 1 diabetes (T1D). Type 1 diabetes is a multi-factorial disease. It is not an
           autosomal recessive disease like CF but genetic predisposition can be one of its
           predisposing features. As with the data on CF, socio-economic deprivation has been shown
           to have a significant adverse effect on outcome in type 1 diabetes. In the US, glycemic
           control amongst young adults was significantly worse amongst disadvantaged young adults
           (27). A retrospective review of New Zealand children with type 1 diabetes also showed
           that poor socio-economic status and Polynesian ethnicity were significantly associated
           with poor glycemic control and long term complications (28).

        3. Chronic kidney disease (CKD). Chronic kidney disease may be due to congenital, acquired,
           or hereditary causes. Within all these groups, socioeconomic status, gender, and race
           may influence disease progression and outcomes. It has been shown in children with
           chronic kidney disease, primarily from the United States, that it was more common in
           low- and middle- income families to have an abnormal birth history such as prematurity,
           low birth weight or small for age which predisposes to the development of renal disease
           (29). In addition, blood pressure control and height deficits improve faster in children
           of families with higher income. In Canada, Aboriginals have a higher prevalence of
           severe chronic kidney disease and a 77% increased mortality risk (30,31) and a lower
           likelihood of nephrology clinic visits (32). Aboriginal children and young adults with
           chronic kidney disease are more likely to have glomerulonephritis as a cause of kidney
           disease compared to Caucasians and are more likely to reach end stage renal disease
           (33). In contrast, lower mortality risks are seen in East Asian and Indo Asian Canadian
           adults starting dialysis (34). There is still much to be studied on the influence of
           these various factors in renal health and disease.

      STUDY DESIGN.

        1. Study Objective. We wish to determine the influence of education, income, race and
           access to health care upon health outcomes in children with chronic diseases in British
           Columbia.

        2. Justification. While the effects of social deprivation on health outcomes are commonly
           discussed, it is surprising how little prospective research there is to quantify the
           adverse effects of social inequity. There is limited prospective data on the effects of
           social deprivation on children in BC and there is none concerning the effects of social
           deprivation on children with chronic diseases. In order to generate firm data relevant
           for those who manage children with chronic diseases in BC, we wish to perform a cross
           sectional observational study of the relationship between social variables and outcome
           in children with cystic fibrosis, type 1 diabetes and chronic kidney disease.

        3. General design. All families in the three clinics will initially be informed of the
           study by letter. When the child is due for regular follow-up assessment, the parents
           will be approached during the clinic visit and invited to join the study. Their
           participation will only involve the completion of a questionnaire. The research
           assistant will collect the data at interview and will subsequently (with parental
           permission) retrieve laboratory results from records of previous clinic visits to assess
           measured health trends over time. The study protocol does not add any further
           investigations other than the questionnaire. Apart from the variable time needed for
           parent information and consent, the questionnaire itself will require no more than about
           30 minutes to complete.

        4. Questionnaire. We will use a socio-economic assessment questions that we are already
           using in our study of quality of life in parents caring for children needing home
           ventilation. It is a conventional form assessing education level, employment, income,
           partnership status and ethnicity. This last is very important because of the poorer
           health outcomes already known to be associated with Aboriginal background. The proxy for
           access to health care will be distance to the main specialty clinic and number of visits
           in the last year.

        5. Analysis. The relationship between socio-economic variables plus ethnicity and outcome
           will be examined using multiple linear regression analysis. In the absence of relevant
           literature, there are too many unknowns to allow any reliable form of power analysis or
           patient number calculation to be performed. One accepted 'rule of thumb' is that there
           should be at least 10 patients for each predictive variable in multiple linear
           regression analysis. We will concentrate on 6 to 8 of the main social factors and will
           try to enroll over 100 patients within each sub-specialty - enough to ensure 15 to 20
           patient outcomes for each variable.
    

Intervention name(s): Social Determinants Questionnaire
Intervention type(s): Other
Intervention description(s): The questionnaire contains a general background information section common to all medical conditions. It then contains separate sections with medical condition specific questions.
Observational model: Family-Based
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Participants will be sampled from the cystic fibrosis clinic (150) patients and the chronic
        kidney disease clinic (150 patients). For the larger type 1 diabetes clinic the sample will
        be purposefully stratified. Recruitment will be monitored to ensure adequate representation
        from all the health authorities in BC.
      
Keywords: Cystic Fibrosis; Diabetes Mellitus Type I; Chronic Renal Insufficiency; The influence of socioeconomic variables upon outcome in children with three chronic medical diseases.