Productivity Costs and Income Losses in Persons with Rheumatoid Arthritis

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Productivity Costs and Income Losses in Persons
with Rheumatoid Arthritis

• Fred Wolfe1, Kaleb Michaud1, Hyon K. Choi2 and
  Rhys Williams3.1National Data Bank for
  Rheumatic Diseases, Wichita KS 2Massachusetts
  General Hospital, Boston MA 3Bristol-Myers
  Squibb, Princeton NJ

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Productivity

• One of the consequences of rheumatoid arthritis
  (RA) is a decrease in productivity
• Productivity refers not only to the work output
  of employed person, but also to the output of
  those who are not working for pay, such as
  homemakers, students and retired persons
• Traditionally, productivity losses have been
  measured by days lost or days limited, but
  this is a crude method and does not account for
  those not in the work force.

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Human Capital Approach

• The Human Capital Approach (HCA) translates lost
  productivity into dollars
• e.g., an hour lost is the equivalent of an hours
  wages
• HCA also considers presenteeism, or decreased
  productivity while employed
• An advantage of HCA is that dollars provide a
  common metric for assessing productivity and
  productivity loss

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Perspective

• Employer decreased production is important
• Societal decreased production and loss of
  productive capacity
• Friction costs and times of high unemployment
  transfer payments
• Patient wages and household income

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Study Aims

• To measure wage and household income income loss
  in RA
• To describe productivity costs as a function of
  wage and income loss
• To measure wage and income loss among the
  non-employed and disabled
• To provide an estimate of productivity loss with
  the Work Limitations Questionnaire
• To provide a reliable measure of productivity
  loss (in dollars) for economic studies

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Methods

• The NDB is a rheumatic diseases research data
  bank that surveys patients semi-annually.
  Responses are validated by outcome assessors and
  by medical record review
• 6,649 RA patients participating in the NDB
  longitudinal study of RA outcomes 1,691
  employed 4,958 not employed

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Major Assessment Questionnaires

• HAQ, HAQ-II, MHAQ, SF-36 PCS and MCS
• Work Limitations Questionnaire (WLQ)
• A 25-item self-administered questionnaire that
  assesses employed persons. The WLQ indicates the
  degree to which health problems interfere with
  specific aspects of job performance. Scores may
  be interpreted as the percent loss in
  productivity compared to a healthy (not limited)
  employee.
• Poverty level (185) HHS guidelines (1998-2003)

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Work and Income Related Variables

• Specific employment
• ONET classification
• ONET, the Occupational Information Network, is a
  comprehensive database of worker attributes and
  job characteristics. It is intended as the
  replacement for the Dictionary of Occupational
  Titles (DOT).
• Annual wages and hours worked
• Total household income

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Expected Wages Direct Method I

• Determined using data from Bureau of Labor
  statistics (BLS) for full time workers during the
  first quarter of 2002, according to the age, sex
  and ethnicity of the RA participants.
• Wages were weighted according the number of hours
  worked and adjusted for an annual increase in
  wages of 2.7 occurring between 2002 and 2003.
• Expected BLS wages do not consider patients
  specific employment

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Expected Wages Direct Method II

• Expected wages using the ONET classification
  system were based on identifying individual RA
  patient occupations and (2001) wages for those
  occupations specified by ONET. Wages were
  adjusted for hours worked and to the year 2002.

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Expected wages and Expected Household Income
Indirect Method

• Expected wages were estimated following
  regression analysis by setting up values for the
  PCS and MCS at which predictions are desired.
• In the analyses of this report those values are
  age and sex specific populations norms of the
  SF36 PCS and MCS.

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Expected wages and Expected Household Income
Indirect Method

• Wages losses represent the difference between the
  SF-36-adjusted predicted wage and the actual
  wage.
• Household income was similarly modeled in working
  and nonworking RA patients.
• We chose to use SF-36 data because of the
  availability of population norms and because the
  HAQ family of questionnaires has unacceptable
  floor effects (clustering at 0).

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Statistical Methods

• The nonlinear relationship between
  wages/household income and age was modeled using
  linear splines with cut points at 40 and 65 years
  of age.
• As income and wages are captured in categories
  that are censored at 100,000, censored interval
  regression was used to model the relationship
  between these variables and predictor variables

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Demographic Characteristics of RA Patients
College graduation rate is 9.7 than US
population. NH whites increased by 9-10.
Median.
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Clinical and Productivity Values for RA Patients
Median
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2002 Median Wages and Household Income Among
1,691 Employed Persons With RA
Expected wages from Bureau of Labor Statistics
(BLS) adjusted to age, sex, ethnicity and hours
worked of the RA sample adjusted to 1st half of
2002. Expected wages from Occupational
Information Network classification adjusted to
hours worked by RA sample adjusted to 1st half of
2002. Based on an annual wage difference of
1,418 due to a 9.2 increase in college
graduates in the RA study sample
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Comparison of Wages Among Persons with RA
According to Current Health Status Compared with
Levels of Health Status in the General Population
Adjusted for age, sex, educational attainment,
marital status and ethnicity. Mean values of
overall US population. For study use, PCS and MCS
were adjusted to age-sex specific norms according
to distribution in the RA subjects.
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Association of Functional Status and Wages among
1,691 Persons with Rheumatoid Arthritis
Adjusted for age, sex, educational attainment,
marital status and ethnicity
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Correlation matrix of Work Limitations
Questionnaire and functional assessment
questionnaires with RA related variables in 1,691
employed persons with RA
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Summary - I

• We have described a new method to model wage and
  income loss in RA based on SF-36 values
• This method was validated by data from the BLS
  and ONET
• Data and methods such as these provide a model to
  predict economic changes related to functional
  status.

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Summary - II

• The annual wage loss in RA is between 3,771 and
  3,852 by the 3 different methods.
• Household income loss was 6,957 overall and was
  4,230 for the employed and 7,726 for those not
  employed.

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Summary - III

• For non-working patients lt 65 years, household
  income loss was 12,266 overall and was 9,908
  for non-working non-disabled persons under age
  65.
• A 0.25 increase in HAQ was associated with a
  1,075 loss of annual wages.
• Workplace productivity (WLQ) was reduced by
  approximately 6.
• HAQ-II, HAQ and SF-36 are more informative than
  the WLQ in regard to wage loss prediction.

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Annual income loss in RA by age, employment
status and disabled status
Income loss measures combined demographic and
health status effect. Income loss measures
effect of health status, not demographic
characteristics.