The association between lower back pain and health status, work productivity, and health care resource use in Japan

Introduction: This study investigated the effect of pain severity on health status, work productivity, health care resource use, and costs among respondents with lower back pain (LBP), in Japan. Materials and methods: Data from the 2013 Japan National Health and Wellness Survey, a survey of Japanese adults, were analyzed (N=30,000). All respondents provided informed consent, and the protocol was institutional review board-approved. Respondents who reported experiencing LBP were propensity score-matched to those without LBP, based on demographics and health history. Using regression modeling, patients with mild, moderate, and severe pain were compared against matched controls, with respect to health status (Mental and Physical Component Summary scores, and health utilities from the Short Form (R)-36 Health Survey version 2), work productivity (Work Productivity and Activity Impairment - General Health version), health care resource use, and annual per-patient costs (estimated using published annual wages and resource use event costs). Results: A total 1,897 patients reported experiencing LBP in the past month (6.32%); 52.45% reported their pain as mild, 32.79% as moderate, and 14.76% as severe. Increasing pain severity was associated with significantly lower levels of mental component scores (46.99 [mild], 42.93 [moderate], and 40.58 [severe] vs 48.10 [matched controls]), physical component scores (50.29 [mild], 46.74 [moderate], and 43.94 [severe] vs 52.93 [matched controls]), and health utilities (0.72 [mild], 0.66 [moderate], and 0.62 [severe] vs 0.76 [matched controls]) (all P<0.05). Indirect costs were significantly higher (P<0.05) among those with moderate ((sic)1.69 million [MM] [equivalent to $17,000, based on United States dollar exchange rates on September 1, 2014]) and severe ((sic)1.88 MM [$19,000]) pain, relative to matched controls ((sic)0.95 MM [$9,500]). Direct costs were only marginally different (P=0.05) between those with severe pain and matched controls ((sic)1.33 MM [$13,000] vs (sic)0.54 MM [$5,000]). Conclusion: Increasing pain severity among respondents with LBP was associated with significantly worse health status, to a clinically-relevant degree, along with greater indirect and direct costs, in Japan.