Dependent variable

In terms of health service utilization, previous studies have usually focused on facility-based outpatient and inpatient services. Most describe the process of visiting a doctor as composed of two steps [32–36]. The first involves a contact decision, i.e. the patient deciding to contact a physician. The second is designated a frequency decision, pertaining to repeated visits or referrals. An intervention may impact on either or both steps and we therefore consider both in this study. The relevant survey questions are:

Outpatient contact decision: In the last month have you visited a public hospital, private hospital, public health centre, clinic, or consulted a doctor or other health worker, or been visited by a doctor or other health worker to provide outpatient care?

Outpatient frequency decision: How many times did you visit or have you been visited during the last month?

Inpatient contact decision: Have you been admitted to hospital in the past year?

Inpatient frequency decision: How many times have you been admitted during the past year?

We will also consider self-treatment because of its high prevalence. For example, in another national survey in China, 27% of respondents reported self-treatment in 2008 [37]. In addition, due to the lower cost, a retirement pension may encourage retirees to try self-treatment before seeking care from a qualified provider. The definition of self-treatment varies [38–41]. According to the World Health Organization (WHO) [42], it is defined as “the activities that individuals, families, and communities undertake, with the intention of enhancing health, preventing illness, limiting illness, and restoring health.” Following this definition, we include the following actions undertaken in the absence of a consultation with a qualified health worker (1): consumption of over-the-counter modern medicines (2); consumption of traditional herbs or medicines (3); consumption of tonics or health supplements (4); using health care equipment.