PHYSICAL TASKS:SURVEILLANCE FOR JOB ANALYSIS AND DESIGN

SURVEILLANCE FOR JOB ANALYSIS AND DESIGN

Provisions of the ANSI Z-365 (1999) Draft Standard

Working Draft ANSI Z-365 includes sections on:

1. Surveillance of musculoskeletal disorders, including:

(a) Worker reports

(b) Analysis of existing records and surveys

(c) Job surveys / proactive entry into the process

2. Job analysis and design, including:

(a) Description of work

(b) Definitions of risk factors

(c) Risk-factor measurement, quantification, and interaction

Musculoskeletal Disorder Surveillance

As discussed in ANSI Z-365 (1999), surveillance is defined as the ongoing systematic collection, analysis, and interpretation of health and exposure data in the process of describing and monitoring work-related cumulative trauma disorders. Surveillance is used to determine when and where job analysis is needed and where ergonomic interventions may be warranted.

A surveillance system can be used in any workplace to evaluate cumulative trauma disorders (musculoskeletal disorders) in the working population. Surveillance is defined as ‘‘the ongoing sys- tematic collection, analysis and interpretation of health and exposure data in the process of describing and monitoring a health event. Surveillance data are used to determine the need for occupational safety and health action and to plan, implement and evaluate ergonomic interventions and programs’’ (Klaucke 1988). Health and job risk-factor surveillance provide employers and employees with a means of systematically evaluating musculoskeletal disorders and workplace ergonomic risk factors by monitoring trends over time. This information can be used for planning, implementing, and con- tinually evaluating ergonomic interventions. Therefore, incidence (rate of new cases), prevalence (rate of existing cases), and parameters that may be used in estimating severity must be defined.

Worker Reports (Case-Initiated Entry into the Process)

Follow-up to medical / first aid reports or worker symptoms consists of collecting and following employee medical reports through the medical management process.

Analysis of Existing Records and Survey (Past Case(s)-Initiated Entry into the Process)

Analysis of existing records and surveys consists of reviewing existing databases, principally collected for other purposes, to identify incidents and patterns of work-related cumulative trauma disorders. It can help determine and prioritize the jobs to be further analyzed using job analysis. There are three types of existing records and survey analyses:

1. Initial analysis of upper-limb WRMDs reported over the last 24–36 months

2. Ongoing trend analysis of past cases

3. Health surveys

Job Surveys (Proactive Entry into the Process)

The aim of proactive job surveys is to identify specific jobs and processes that may put employees at risk of developing WRMDs. Job surveys are typically performed after the jobs identified by the previous two surveillance components have been rectified. Job surveys of all jobs or a sample of representatives should be performed. Analysis of existing records will be used to estimate the potential magnitude of the problem in the workplace. The number of employees in each job, department, or similar population will be determined first. Then the incidence rates will be calculated on the basis of hours worked, as follows:

This is equivalent to the number of new cases per 100 worker years. Workplace-wide incidence rates (IRs) will be calculated for all cumulative trauma disorders and by body location for each department, process, or type of job. (If specific work hours are not readily available, the number of full-time equivalent employees in each area multiplied by 2000 hours will be used to obtain the denominator.) Severity rates (SRs) traditionally use the number of lost workdays rather than the number of cases in the numerator. Prevalence rates (PRs) are the number of existing cases per 200,000 hours or the percentage of workers with the condition (new cases plus old cases that are still active).

ANSI Z-365 Evaluation Tools for Control of WRMDs

Some of the research evaluation tools defined by the ANSI Z-365 Draft Standard for the purpose of surveillance and job analysis include the following:

1. Proactive job survey (checklist #1)

2. Quick check risk factor checklist (checklist #2)

3. Symptom survey (questionnaire)

4. Posture discomfort survey

5. History of present illness recording form

Analysis and Interpretation of Surveillance Data

Surveillance data can be analyzed and interpreted to study possible associations between the WRMD surveillance data and the risk-factor surveillance data. The two principal goals of the analysis are to help identify patterns in the data that reflect large and stable differences between jobs or departments and to target and evaluate intervention strategies. This analysis can be done on the number of existing WRMD cases (cross-sectional analysis) or on the number of new WRMD cases in a retrospective and prospective fashion (retrospective and prospective analysis).

The simplest way to assess the association between risk factors and WRMDs is to calculate odds ratios (Table 29). To do this, the prevalence data obtained in health surveillance are linked with the data obtained in risk-factor surveillance. The data used can be those obtained with symptom ques-

tionnaires (active level 1 health surveillance) and risk-factor checklists (level 1 active risk-factor surveillance). Each risk factor could be examined in turn to see whether it has an association with the development of WRMDs. In the example shown here, one risk factor at a time is selected (overhead work for more than four hours).

Using the data obtained in surveillance the following numbers of employees are counted:

• Employees with WRMDs and exposed to more than four hours of overhead work (15 workers)

• Employees with WRMDs and not exposed to more than four hours of overhead work (15 workers)

• Employees without WRMDs and exposed to more than four hours of overhead work (25 work- ers)

• Employees without WRMDs and not exposed to more than four hours of overhead work (85 workers)

The overall prevalence rate (PR), that is, rate of existing cases, for the firm is 30 / 140, or 21.4%. The prevalence rate for those exposed to the risk factor is 37.5% (15 / 40) compared to 15.0% (15 /100) for those not exposed. The risk of having a WRMD depending on exposures to the risk factor, the odds ratio, can be calculated using the number of existing cases of WRMD (prevalence). In the above example, those exposed to the risk factor have 3.4 times the odds of having the WRMD than those not exposed to the risk factor. An odds ratio of greater than 1 indicates higher risk. Such ratios can be monitored over time to assess the effectiveness of the ergonomics program in reducing the risk of WRMDs, and a variety of statistical tests can be used to assess the patterns seen in the data.