The health needs of elderly people are considered a "secondary requirement" in some of Britain's care homes, a report has found.
Certain institutions fail to meet even basic standards and only about a third of homes reported routine visits from GPs.
Those who need an initial continence assessment are forced to wait more than two weeks for it in nearly 40% of establishments.
A quarter of residents, many of them elderly and vulnerable, feel they were not offered a choice of male or female assistance when using the toilet.
The Care Quality Commission (CQC) study also revealed striking geographical differences in treatment, with many homes unable to offer access to geriatric specialists.
The review comes just days after a landmark report called for fundamental change to the care of older people.
Amanda Sherlock, CQC director of operations, said: "While we have identified good practice in areas, this review suggests some providers have fallen short of delivering effective care by considering the healthcare needs of residents as a secondary requirement.
"Despite having a disproportionately high level of dependence on health services, this group appear to be more disadvantaged than the rest of the population in accessing these services."
The CQC interviewed or observed care being delivered to 386 residents in 81 homes within nine PCT areas which were considered at risk of poor performance.
Three residential care homes, three nursing homes and three homes for learning-disabled people were examined in each PCT.
The investigation, conducted last year, identified good practice in areas such as care planning but found access to some services "appeared to be too variable" and, in some areas, basic health needs were not met.
In many establishments, the views of the person's relatives and carers were not taken into account; 30% of nursing homes did not have a Do Not Attempt Resuscitation policy in place; 35% of homes indicated that getting medicine to residents on time was "sometimes" a problem; and only half (52%) provided staff with training about stroke.
Just 60% of PCTs ensured access to a geriatrician.
Meanwhile, staff in some homes admitted they are not confident that they understand the needs of the people living there.
The British Geriatrics Society (BGS), which analysed the CQC data for its report, Failing The Frail: A chaotic approach to commissioning healthcare services for care homes, said healthcare needs of older care home residents are being "neglected" in some areas.
"The data shows that PCTs do not accord sufficient priority to care home residents when planning and ensuring the delivery of local healthcare services," it added.
"This has resulted in considerable variation in the extent to which their healthcare needs are being met."
Professor Finbarr Martin, BGS president, said: "The data set which we analysed confirms our fears that the healthcare needs of older care home residents are being neglected in some areas."
While he noted "pockets of excellent NHS care" in areas such as Sheffield, Leeds or south Manchester, he said there were "striking geographical differences".
He added: "It is unacceptable to leave people waiting for over three months to receive treatment which could significantly improve their quality of life, especially when you consider that the average life expectancy of an older person entering a care home is between one and two years.
"It is time that commissioners and health service planners matched their obligations to ensure that the healthcare needs of this vulnerable group are adequately met."
Only last month the Commission on Dignity in Care made a series of recommendations which included establishing a care quality forum to look at all aspects of care home staffing.
Its report also said patronising language used by staff towards older people should be banned.
The CQC will use its review to identify areas for consideration in its inspection programme which will examine dignity and nutrition in 500 care homes.
The PCTs examined for the study are: Birmingham East and North, Greenwich, Luton, North East Essex, Nottinghamshire County, South Tyneside, Southwark and Warrington.