Decreased work ability associated to indoor air problems--An intervention (RCT) to promote health behavior

Introduction: Indoor air problems may induce respiratory irritation and inflammation. In occupational settings, long-lasting non-specific building-related symptomatology, not fully medically explained, is encountered. The symptomatology may lead to illness, avoidance behavior and decreased work ability. In Finland, investigations of workers suspected of occupational asthma have revealed excess disability. There are no well-established clinical practices for the condition.

Objective: The aim was to develop a clinical intervention for patients with non-specific indoor air-related symptoms and decreased work ability.

Methods: A randomized controlled trial including psychoeducation and promotion of health behavior was carried out in 55 patients investigated for causal relationship between work-related respiratory symptoms and moisture damaged workplaces. Inclusion criteria for disability was the work ability score (WAS)≤7 (scale 0-10) and indoor air-related sick leave ≥14 days the preceding year. After medical evaluation and the 3-session counseling intervention, follow-up at 6-months was assessed using self-evaluated work-ability, sick leave days, quality of life, and illness worries as outcome measures.

Results: The mean symptom history was 55.5 months. 82% (45 out of 55) had asthma with normal lung function tests in most cases, although reporting abundant asthma symptoms. 81% of patients (39/48) had symptomatology from multiple organ systems without biomedical explanation, despite environmental improvements at work place. At the psychological counseling sessions, 15 (60%) patients of the intervention (INT, n=25) group showed concerns of a serious disease and in 5 (20%), concerns and fears had led to avoidance and restricted personal life. In the 6-month follow-up, the outcomes in the INT group did not differ from the treatment as usual group.

Conclusion: No intervention effects were found. Patients shared features with medically unexplained symptoms and sick building syndrome or idiopathic environmental intolerance. Long environment-attributed non-specific symptom history and disability may require more intensive interventions. There is a need for improved recognition and early measures to prevent indoor-associated disability.

Trial registration number: Single-center randomized controlled trial (ISRCTN33165676).