Table 2
Association of contracting out cleaning services with other outcomes.

Hand-washing availability
Staff-Reported Excellent cleanliness bathroom
Patients reported Excellent cleanliness room
Patients reported
Mean variation due to contracting-out cleaning services vis-a’-vis retaining them in house −1.22%* (0.30) −0.45%*
(0.003) −0.76%***
Number of Trust-years 362 446 446
Notes: Source: Data from Hospital data from Patient Environment Action Teams (PEAT) dataset (from 2010 till 2012), Patient-Led Assessments of the Care Environment (PLACE) (2013–2015), ERIC (Estates Return Information Collection) (2010–2015), NHS Inpatient Survey (2010–2014), NHS Staff Survey (2010–2014), and Public Health for England (2010–2014). Bootstrapped SE-values in parentheses (250 replications), stratifying by type of cleaning service. Coefficients represent average variation in MRSA incidence rate between Trust which outsource their cleaning services and those which retain their cleaning services in house. The dependent variable represents: the percentage of staff reporting that hand-washing material is always available (column 1), percentage patients reporting excellent cleanliness of the bathroom they use (column 2) and percentage patients reporting excellent cleanliness of the room or ward they stayed (column 3). Trust are matched through Propensity Score Matching and their distribution are aligned by region, number of beds, number of specialist sites, number of multi sites. After having aligned the distribution we regress, through a linear model, the dependent variable on the number of beds, average length of stay, regional and year dummies.


Our evidence indicates that in outsourced Trusts fewer people report ready access to hand-washing material (i.e. our proxy for the shortage of handwashing materials) by about 1.22% (95% CI –1.79% to −0.58%), and about 1 percentage points fewer patients reporting excellent cleanliness for the bathrooms (−0.45% percentage of patients reporting excellent cleanliness 95% CI: −0.46% to −0.44%0) and for rooms/wards (−0.76%, 95% CI: −0.01% to −0.002%). Translating the coefficients into the original framework, we find that while 61.3% of the outsourced Trusts will report having hand-washing material always available, their in-house peers will have 62.7%. The percentage of patients reporting excellent cleanliness in the bathrooms (rooms) are 58% (66.8%) and 58.49% (67.5%) respectively.

3.3. Comparing economic costs
Since one of the main arguments for outsourcing cleaning service in hospitals was to reduce costs, we also estimate the association between outsourcing of cleaning services on the cleaning cost per bed (see column 1 in Table 3) and cleaning personnel (column 2). The variation in percentage points is presented in web appendix table 6.

Our models estimate that outsourced Trusts have a lower cost of cleaning per bed of about £236 per bed per year (95% CI: £294 to -£172), and employ fewer cleaning staff, by about −0.006 people (95% CI: −0.008 to −0.001). Translating these coefficients into predictions, we find that the average cost per bed for Trusts that outsourced their cleaning services is about £2,894, while the average cost per bed for their in-house counterpart is about £3130. Here, adjusting for potential confounding factors appear to be particularly relevant, since the unadjusted comparison between the two average cost would have been misleading. With respect to the cleaning staff employed, we predict that outsourced Trusts would employ 0.126 staff per-bed, while in-house Trusts would employ 0.133 staff per-bed.