This late in the season it's not uncommon to have tattered leaves spotted by disease.
While Ninebarks can get leaf spot diseases and cankers, it's a pretty tough plant.
It is also normal to have peeling bark with age. We can't tell if they are dead or just peeling.
Do those branches have leaves? Scrape bark with your fingernail to look for green tissue beneath. If it's black or brown, it's likely dead and can be pruned out at any time.
Otherwise, you might consider renewing the shrub by cutting it to the ground in the late winter.