Objective: Chronic pain conditions, such as osteoarthritis (OA) and mechanical chronic low back pain (CLBP), among active workers cost employers ~$61.2 billion/yr in lost productive time, which includes both reduced performance while at work and days of work missed (absenteeism). An analysis of lost productivity time from a 56-week, open-label study was conducted to calculate the potential economic effects of treatment with HC/APAP CR to employers. Methods: As part of a larger clinical trial reported elsewhere, the Work Productivity and Activity Impairment (WPAI) instrument was administered at baseline and weeks 24 and 56 to measure reduced productivity and overall work impairment due to health. Results are reported as percentage of lost productivity time and estimated economic impact to employers. Using the 2006 U.S. average weekly wage of $861, the mean costs of reduced productivity and overall work impairment due to health were calculated. The economic impact of improved work productivity and overall work impairment due to health after treatment with HC/APAP CR was calculated as the difference in cost from baseline to week 24 and week 56. Results: Impairment while working due to health decreased from baseline by 17.4% at week 24 and 16.6% at week 56. This translates into an estimated cost-savings (per employee) to employers of $3527 at week 24, and $8019 at week 56. Similarly, overall work impairment due to health decreased from baseline by 17.5% at week 24 and 15.8% at week 56. This translates into an average potential savings to employers of $3614 at week 24 and $7596 at week 56. Absenteeism decreased by 1.1% at week 24 and by 0.04% at week 56. Conclusion: As assessed by WPAI instrument, this subanalysis demonstrated 12-hour, extended-release HC/APAP CR improved work productivity after 24 and 56 weeks of treatment in patients with OA and CLBP.