The Migraine Module of the Productivity Impact Model was developed based on peer-reviewed literature and available pharmaceutical data. Our goal was to develop a methodologically sound, conservative model to estimate the impact of migraines and the benefits of acute treatment in the workforce. However, as with any calculator, there are some limitations to keep in mind.

1. The model focuses on one type of acute treatment (triptans) and this treatment may not be appropriate for all migraineurs. We have assumed that people with moderate or severe headache pain will benefit from triptan treatment. This is based on formal treatment guidelines. However, some people we have included in our calculations may have success treating their migraines with other medications, or may have frequent enough headaches that prophylactics are more appropriate.
    
2. Not all people will experience the same improvement in productivity when their headaches are treated with triptans. We have combined measurements from a number of different studies to develop the expected improvement in absenteeism and presenteeism as a result of treatment. The 49% improvement used as our baseline is an average that may over or underestimate the impact in some people.
    
3. The model uses data from a variety of studies, most of which are based on self-reported information from migraineurs. Migraineurs generally report a high level of pain and severity associated with their headaches, but a relatively large percentage report they did not miss a day of work due to headaches. There may be some reporting bias that results in an underreporting of days missed on the job or productivity impacts. If so, the calculations of the net benefit from treatment are likely to underestimate the improvement in absenteeism and presenteeism from treatment.
    
4. The Migraine Calculator methodology relies on the human capital approach to represent the value of time missed from work, or from lowered productivity. This approach assumes that an employee’s compensation is directly related to the output, or productivity, of that employee.

   When an employee is absent the firm may replace the employee with a temporary worker, incurring replacement costs that are likely to be equal to or higher than the absent employee’s compensation. Or, the firm may elect not to replace the employee, and suffer a loss in output which is also related to the employee’s compensation. In both of these cases the employee’s daily compensation is used as a proxy for the impact to the firm.

   Can the firm “get by” without replacing the worker at all, relying on co-workers to help make up the work or by deferring the work to another day? Almost every workplace has experienced this to some degree. However, the overall management of a workforce (especially for larger companies) does not typically rely on stopgap measures. A firm that experiences a significant number of lost days due to absenteeism or presenteeism will be facing either replacement costs or loss of output.
    

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