Relationship between complaints and quality of care in New Zealand: a descriptive analysis of complainants and non-complainants following adverse events

Objectives: To estimate the proportion and characteristics of patients injured by medical care in New Zealand public hospitals who complain to an independent health ombudsman, the Health and Disability Commissioner ("the Commissioner''). Design: The percentage of injured patients who lodge complaints was estimated by linking the Commissioner's complaints database to records reviewed in the New Zealand Quality of Healthcare Study (NZQHS). Bivariate and multivariate analyses investigated sociodemographic and socioeconomic differences between complainants and non-complainants. Setting: New Zealand public hospitals and the Office of the Commissioner in 1998. Population: Patients who lodged claims with the Commissioner (n=398) and patients identified by the NZQHS as having suffered an adverse event who did not lodge a complaint with the Commissioner (n=847). Main outcome measures: Adverse events, preventable adverse events, and complaints lodged with the Commissioner. Results: Among adverse events identified by the NZQHS, 0.4% (3/850) resulted in complaints; among serious, preventable adverse events 4% (2/48) resulted in complaints. The propensity of injured patients to complain increased steeply with the severity of the injury: odds of complaint were 11 times greater after serious permanent injuries than after temporary injuries, and 18 times greater after deaths. Odds of complaining were significantly lower for patients who were elderly (odds ratio (OR) 0.2, 95% confidence interval (CI) 0.1 to 0.4), of Pacific ethnicity (OR 0.3, 95% CI 0.1 to 0.9), or lived in the most deprived areas (OR 0.3, 95% CI 0.2 to 0.6). Conclusion: Most medical injuries never trigger a complaint to the Commissioner. Among complaints that are brought, severe and preventable injuries are common, offering a potentially valuable "window'' on serious threats to patient safety. The relatively low propensity to complain among patients who are elderly, socioeconomically deprived, or of Pacific ethnicity suggests troubling disparities in access to and utilisation of complaints processes.