Abstract: Five randomised trials and four controlled before and after studies were included. The interventions were complex. Five studies added an additional component, or linked a new component, to an existing service, for example, adding family planning or HIV counselling and testing to routine services. The evidence from these studies indicated that adding on services probably increases service utilisation but probably does not improve health status outcomes, such as incident pregnancies. Four studies compared integrated services to single, special services. Based on the included studies, fully integrating sexually transmitted infection (STI) and family planning, and maternal and child health services into routine care as opposed to delivering them as special 'vertical' services may decrease utilisation, client knowledge of and satisfaction with the services and may not result in any difference in health outcomes, such as child survival. Integrating HIV prevention and control at facility and community level improved the effectiveness of certain services (STI treatment in males) but resulted in no difference in health seeking behaviour, STI incidence, or HIV incidence in the population. There is some evidence that 'adding on' services (or linkages) may improve the utilisation and outputs of healthcare delivery. However, there is no evidence to date that a fuller form of integration improves healthcare delivery or health status. Available evidence suggests that full integration probably decreases the knowledge and utilisation of specific services and may not result in any improvements in health status. More rigorous studies of different strategies to promote integration over a wider range of services and settings are needed. These studies should include economic evaluation and the views of clients as clients' views will influence the uptake of integration strategies at the point of delivery and the effectiveness on community health of these strategies.

Plain-language summary: This updated review included nine studies that evaluated integrated care or linkages in care. The studies made two types of comparison. 1) Integration of care, by adding a service to an existing service (tuberculosis (TB) or sexually transmitted infection (STI) patients were offered HIV testing and counselling; mothers attending an immunisation clinic were encouraged to have family planning services). 2) Integrated services versus single, special services (family planning, maternal and child health delivered as a special vertical programme or integrated into routine healthcare delivery). There was some evidence from the included studies that adding on services or creating linkages to an existing service improved its use and delivery of health care but little or no evidence that fuller integration of primary healthcare services improved people's health status in low- or middle-income countries. People should be aware that integration may not improve service delivery or health status.If policy makers and planners consider integrating healthcare services they should monitor and evaluate them using good study designs. A summary of this review for policy-makers is availablehere