This review investigated whether type of hospital (for-profit, not-for-profit, governmental) affected patient outcomes in the US, and what factors might explain any variations. Differences in data sources, time period and region caused differences in patient outcomes between hospital types. The lack of a validity assessment meant that the findings should be interpreted with caution.

To examine which factors affect the differing associations between hospital ownership and quality of care.

Medline, EconLit and ProQuest/ABI were searched; keywords used were listed in the review. Some handsearching was performed (though it was not specified what was searched), reference lists of previous qualitative reviews were screened and authors were contacted to ask for additional or unpublished work. Only studies in English were eligible for inclusion.

Studies which compared hospital performance across at least 50 general, acute, short-stay hospitals in at least two ownership categories (government funded, private not-for-profit and private for-profit) in the USA were eligible for inclusion. Studies that compared sub-categories of ownership or those on hospitals of the Department of Veteran Affairs were not eligible for inclusion.

Studies needed to report patient outcomes (mortality, complications or other adverse outcomes) as indicators of hospital performance to be included in the review. Outcomes in the selected studies included mortality rates and other adverse patient outcomes, such as surgical complications or medical errors.

Two reviewers selected the studies for inclusion in the review and discrepancies were resolved by consensus.

The authors did not state that they assessed validity.

Data required to construct measures of treatment effect were extracted. A partial correlation coefficient of the association between the ownership variable and the outcome (standardised to a z-score) was calculated for each study. Formulae were provided in the review. Whether each study included information on pertinent design features (those analysed in the meta-regression) was coded as binary variables. Only main (not sensitivity) analyses were extracted from each study. The authors did not state how many reviewers performed the data extraction.

Reasons for differing results between studies (the primary aim of this review) were analysed using random-effects meta-regression. The pooled results from meta-analyses were not presented. The standardised effect size from each study was used as the dependent variable in the meta-regression analysis. Empirical features of each study acted as explanatory variables.

Publication bias was assessed using the Card and Krueger method. The proportion of variation between the studies explained by the factors studied was measured using the I² statistic.

Thirty one studies were included in the review. Analyses covered the period 1981 to 2001.

Overall there was no association between hospital ownership and either mortality or other patient outcomes (pooled effect sizes were not reported).

Meta-regression revealed that studies using National Long-term Care Survey data showed patient outcomes that were significantly better in for-profit hospitals compared to private not-for-profit hospitals. In studies that were representative of the US as a whole (rather than studies of single states), patient outcomes were significantly worse in for-profit hospitals compared to those for private not-for-profit hospitals.

Studies that involved Medicare claims showed that patient outcomes were significantly worse in governmental hospitals compared to private not-for-profit hospitals. Studies based on only 1980s data showed that patient outcomes were significantly better in governmental compared to private not-for-profit hospitals.

There was no evidence of publication bias.

Associations between hospital ownership and and adverse patient outcomes differed according to a study's data source, the time period studied and the region of the US that was studied. Studies that were representative of the US as a whole showed that for-profit hospitals had worse patient outcomes than not-for-profit private hospitals.

The review question was clearly stated and inclusion criteria were adequately defined. The use of two reviewers performing the study selection the risk of errors. The authors appeared to make an effort to identify published and unpublished data. There was no evidence of publication bias in the results. The nature of the search (including contacting previous authors and handsearching) meant that it was not fully reproducible. The language restriction was unlikely to have introduced language bias, because only US studies were eligible for inclusion.

As no validity assessment was made of the included studies, it was not possible to comment on the reliability of the results. The statistical methods used appeared to be appropriate.

Given the lack of validity assessment, the results should be interpreted with caution.

The authors did not state any implications for practice or further research.

The work was funded by a grant (#050953) from the Robert Wood Johnson Foundation’s Changes in Health Care Financing and Organization Initiative.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.